I never considered owning an RV before I began to travel for dog trials. I had no desire to camp for fun. I started trialing about 7 years ago and am currently on my third travel trailer. I use it solely to travel and stay on site at trials.
Being an absolute trailer novice, I started out with a very small 13 foot trailer which had no bathroom, refrigerator or heater, but it was easy to tow and park, and provided a dry place to sleep. After two years of bathing in my sink, I upgraded to a 21 foot self contained trailer (self-contained means it has a bathroom!) Last year, I upgraded again to a 28 foot trailer with a slide out room. Everyone's preferences and priorities are different, but here are my thoughts on what's important to look for when you're shopping for a trailer and some of *my* likes and dislikes-
How much can your vehicle tow?
Check your owner's manual. The imprinted stamp on your bumper which says your bumper is rated to tow 3500 lbs may not mean your mini van can safely tow a 3500 lb. trailer. Your owner's manual will give you the correct numbers. You will have to know your engine size and axle ratio. Your owner's manual will provide you with a maximum trailer weight (of a fully loaded trailer) your vehicle can manage as well as a Gross Combined Weight Ratio (GCWR) which is the maximum your vehicle plus a fully loaded trailer can weigh. When you shop for RV, you'll notice every trailer has a square white sticker on it somewhere (tongue, side or back) which provides information about how much the trailer weighs both empty and loaded, as well as tongue weights and axle weights. The size and weight of the trailer will determine what type of hitch and hitch accessories you will require. Don't try to tow more than your vehicle can handle. It's extremely dangerous and will cause endless problems with your vehicle.
Actual Trailer Length and Width
Some manufacturers measure their units differently so check to see if the stated length is the actual living area, or the length from the tongue to the bumper. Width makes a huge difference in the "feeling" of space, even an extra 6 inches makes a big difference. Most units are between 7 & 8 feet wide. You will be amazed at how much more spacious an 8 foot wide trailer feels vs. 7 foot wide. You may be able to tolerate a shorter trailer if it's a wider one.
Living Area Configuration
The more you shop, the more you will see the same basic floor plans repeated. My preference is to have the maximum amount of open floor space, so I tend to like units with a bed on one end and bathroom at the opposite end. Another popular arrangement is to have a living area on one end, bath in the mid section and bedroom at the opposite end. This option provides more privacy. My second trailer had a bed set into a corner of one end. Everyone told me I'd hate it and believe me, I did. In fact, almost everyone I know who has this floor plan hates it. It's a huge pain to change bedding, and was a factor many dealers commented on as hurting trade in value. If possible, find a bed that you can walk around on 3 sides. If you're looking at small trailers with no permanent bed, consider the amount of hassle required to convert a couch or table into a bed. Don't take the dealer's word for it, try doing it yourself. Some items convert much easier than others.
Another big factor for me was carpet. I wanted as little as possible. My dogs stay inside the trailer & linoleum is infinitely easier to clean. Also, I learned with my second trailer that there is common problem with moisture damage in many lightweight models with linoleum floors. Damage usually shows up when the unit is 4-5 years old. Dealers change out the linoleum & buyers don't know about more serious moisture damage in the floor & under frame. If you're buying a used trailer beware of new linoleum as it may be hiding a bigger problem .
Slide outs create significant space, but also add weight and a potential for leaks. Fortunately, most of the bugs with slides seem to have been worked out over the years & nearly all the service department staff I spoke with reported relatively few problems with slides.
Toilet/Shower Set Up
Some smaller trailers have a combined shower/toilet area. While in my opinion, having any toilet/shower is better than having none, most people prefer a separate shower.
Windows & Ventilation
Remember your trailer's A/C runs off an electric hookup, so if you're not hooked up or plugged into a large generator, you won't have A/C. Check for window placement & how they open (out or slide) for ventilation. Also pay attention to window placement in relation to the awning arms and door. Windows that open out are better for keeping rain out, but may interfere with awning arms & propping doors open, and thus are useless much of the time. My new trailer has some windows that slide and others that open out depending on their location.
Roof Vents, Front Windows, Roof A/C
Most water leaks show up around these areas. If you're looking at used trailers, check for water damage or signs of recent caulking that may be hiding water damage. Many new trailers are built without front windows. Several dealers I spoke with reported this as their biggest problem area for leaks, so I opted for no front window in my latest model.
Some lightweight units use 13 or 14 inch tires. While they may suffice on the smallest units, 15 inch tires are best. If buying a used trailer, look for uneven treadwear on smaller tires. Could be evidence of a bent frame. Also, double check if a spare is included. Many new units don't have a complimentary spare & believe me, you need one! Look under a used trailer for signs for frame repair, rust or badly configured electrical wiring.
Furnace, Water Heater and Refrigerators
How do they light? Most new units light from inside...easy, just push a button. Many older units have to be manually lit from the outside. Also, better refrigerators have a separate refrigerator/freezer area. Those that are combined in one door may have problems with condensation & mold.
Size of tanks (LP, fresh, black & grey)
Remember that your furnace & refrigerator will run off the LP tanks unless you're hooked up to an electrical source. Check number of LP tanks & size. Also, where are LP tanks located? Tanks stuck in an interior storage compartment are awkward to fill and waste storage space. I prefer LP tanks mounted on the hitch. Also check where the battery is mounted. Note the size of fresh water tanks as well as the "dirty" water storage tanks. Water use varies hugely from person to person. Remember big water tanks, when full, will add considerable weight to your trailer.
When I was trailer shopping, I checked N.A.D.A. depreciation percentages on several different models. There's a BIG difference. Logically, better units will depreciate less. If you see an usually high depreciation rate, likely it's a troublesome model. Also, models with canvas slides have higher depreciation rates than hard sided models. Talk to folks who have owned them. While they provide more living space and may be more economical, I don't know anyone who bought a second one after owning one!
Most banks charge a significantly higher interest rate on RV s than they do on cars. It's worth shopping around. I found one that financed all titled vehicles at a car rate. It was a considerable interest savings. Also check with your accountant to determine if the interest on your self-contained RV is deductible in the same way as mortgage interest on a second home may be.
Ask your dealer frankly what models he sees most commonly back for service and what the problems are. I visited several dealers and heard a lot of the same responses, and quickly marked those models off my list of possibilities.
Remember there is an enormous mark up on new trailers, so feel confident in having some serious negotiation room when you sit down to work up a deal. When you think you've reach the bottom dollar price the dealer will accept, try getting him to throw in some accessory extras and have them installed. (Hitch accessories or roof vent covers are good examples.) There's also a big mark up on them, so it's really not costing him much & may save you hassle on something you would have to buy anyway.
Good luck shopping!