A few things
This is the end of summer and the deals should be there as peoples interest in summer toys wanes. The dealers here drop their prices so the trailers don't sit on the lot all winter.
We bought new in August of 2011 and the prices dropped some each week. When they sold out of the more popular 21 ft we liked, they dropped the price on a 25 ft to even less. They went down another $500, got us 4.5% at a credit union and had the rig ready to go 3 days later as part of the deal.
The Wholesalers did offer a lower price up front and we would have saved some even after delivery but once you compare their 7,99% 12 year loan vs the 4.5% 5 year loan we got, we could buy another trailer with the difference.
If you are going to buy used, do it right and get on craigslist, find a RV trader or the want ads and buy from a private party. It takes more effort than roaming around a lot with the kids but you will get a much better deal. The dealer has to get a profit out of his and the less you know the better. (often I see the WDH going with a used rig)
Find a trailer you like, it's time for the teach to do his homework. Type in any year, make and model to your search and you will find everything from the specs, praises and complaints, selling value, etc. Brushing up on the basic systems so you can test them when you look would be good too.
I understand what you are saying about slides, room and cabin fever. We don't have a slide and it has rained almost every afternoon this year while we camped. At first we thought a slide would help but honestly a few more feet isn't going to cut it. What does is having a distraction and being comfortable and I've never sat in a dinette that was. So when you find a rig you like, get everyone in it and close it up for a hour or so and just sit there. After that realize that there will be whole days that it will rain.
With a big family and a limited vehicle capacity, I wouldn't put anything but them in the truck. 100 pounds in the back of the truck comes directly off of the payload, rear axle and reduces how much tongue weight you can have. Put it the trailer and the truck will never know. Pushing your truck to it's limits might be fine for normal driving but get into a emergency situation and it may be interesting to say the least.
Good luck with your search.
