Don't know exactly where you are, but a place to look for gently used would be at PPLMotorhomes.com They are a huge consignment lot with a good reputation. At least you can find something in your price range and it will give you some insight. As far a recomendations for brands, that will be your choice if the fit and finish are what pleases you. Trailer or 5th wheel is another choice, with motor homes another whole ball of string. Since you will be in it a lot, look for rigs rated for full timiing, or at least with adeded insulation and enclosed underbellies. Carriage, Excel, older Sunnybrooks, Montana and I am sure others may be good choices for extended use. Just stay away from "extra lite" construction as it will be hard to heat and cool, especially since you said southwest area.
We re-entered the RV life when my work took me out of town a lot. Found the RV was a good method of surviving. I had enough of a nasty motels and greasy spoon dining.

You would want at least a 25 foot whatever to provide enough room for everyone. Look for a wide open floor plan versus one where the manufacture tries to cram everything in. A nice option is a toy hauler style RV because it provides flexibility. The garage area can be a bedroom for the kids or additional living space.

We always look for a large bathroom, with a big shower. My dad had a motorhome where there was a wall in front of the toilet that was so close you had to turn sideways to sit. In addition another wall protruded into this miniture bath tub that also served as a shower. It was OK as a shower but only small children could have used it as a tub.

Some of the 5th wheels made during the last 5 years come with a single or double bedroom in the back for kids. Some even have a toilet and sink area for the kids use. A 5 year old 5th wheel may fall in the upper end of your price, but then you'll need a truck to pull it with.

Craigslist is another choice to find RVs.

BearII I agree with most of what you said, you offer a lot of good choices. However, the OP said they had never set foot in an RV. For that reason alone, Craigslist would be a poor choice. On it, you are looking only at price, with no indication of comparative pricing versus quality versus condition. At the very least, PPL gives an "opinion" about condition. Now for those of us that are "experts" (where is that tongue in cheek smilie when needed?) Craigslist might be a good shopping venue. I am sure there are other consignment lots out there that offer some semblance of valuation. For new RVers, any help is a good thing. I would hate to see someone get stung by purchasing a sub-quality RV and get a sour taste from it. This forum is a place for all of us to learn, hopefully not from someone else's bad luck.

Merc you're right... I should have also indicated for them to use an RV mechanic or inspection service to confirm the condition of any used RV they find.

You do need to shop around to find something that fits just right....RV shows, RV dealers, Consignment lots and internet searches are all useful.