welcome to BHQ
For a first trip I would opt for the best western in St Anthony, its right on the strip to the dunes. Its nice if you dont have a RV, the price is very reasonable, AC and a shower and a bed to sleep in. I would go for the haulers for strictly hill climbing and something like a sand star for every thing else. sand stars allow you to side hill where the haulers tend to slide the ass end out on you. Start the mornings with about 8-10lbs of air in your tires then less as it gets hotter in the day. the elevation at St A's is right at 5,000ft wich is a 190 jet I think, ask your local shop. There is Rexburg motor sports if you need anything, about 15 mins away. If you like to cut loose there is only 2 bars in St A's and there like a block from the best western. We like to go the monday right after memorial weekend, its alot less people and always seem to be a nasty ass storm the holiday weekend. we had nothing but hail/snow this year. MUST have a flag and registration, if your state doesnt have ORV stickers you can buy a ID sticker for under $20
If you have any other questions feel free to ask. We will be there again for 07' if you decide to go then we could get together for a first ride tour.
here is a some St A dune videos
http://www.dunereview.com/saintanthonyvideos.htm