I'm sure you'll get many replies, but since we are first here's our perspective:
Age - believe it or not, you're right in the middle of the Desire "sweet spot" as the majority of couples are between 35 and 45, yes there will be some younger and some older but what you'll hear is that age doesn't matter (most of the time) as it's all in the attitude of the person.
First time - can't emphasize how important it is to communicate with each other BEFORE you get there, during your stay each and every day. Set boundaries and stick with them unless you talk about changing them. We have had more than 16 or 17 trips and that is the #1 piece of advice we can offer....we still discuss things before each trip!
Resorts - we are splitting our trip, two nights at Pearl to start off with and then heading to RM for four nights. RM is the original and is generally very busy during the summer months so no need to worry about a group or takeover AND as your first time I would avoid a takeover week as it MAY be a little overwhelming. No worries about RM being slow, Pearl on the other hand does not have the vibe yet that RM has so I would recommend going as from all accounts it's a wonderful resort with great ammenities but just not "amped up" yet like RM.
Items to consider - don't over-pack, big mistake first time couples make. It's clothing optional so go at your own speed, you won't be pressured to do anything you're not comfortable with! Take insulated mugs (Tervis, Bubba Keg, etc..) as drinks are served in plastic (hard) cups but the sun/heat melts the ice quickly and you go through them pretty quickly. A 24 - 48 ounce insulated mug keeps your drink cold and will you'll have fewer trips to the bar. Load your iPod with music and take it for your in room music while getting ready or entertaining

Try all the restaurants and take the time in the afternoon for a trip on one of the catamaran's at the resort, nice break in the day.
People - you'll meet some of the coolest people on earth. Most everyone is very friendly and conversations are easy to start.....you'll find that it's not how much you make, how big your house is or what kind of car you drive, it's all about getting to know the person you're talking with and leaving all that bullshit behind! Anyway, that's our take on it!
Sorry for the long winded reply but once I started it just kept going! Get ready for the best vacation you've ever had and I warn you that it will be very difficult to vacation at a vanilla resort ever again after visiting Desire....just saying!
E&J
