I haven't made it to both previous runefests because of limited funds, but I'd definitely love to go to the 2012 event if its in the US.
On the suggestive side I have some ideas based off your review.
-For free food/drinks you could be given noted beer (If you meet the drinking age) or soda (If you prefer so or don't meet the drinking age) and noted foods like cheeseburgers and chicken.
-Adult activities and normal activity suggestions -Paintball fights with paintball guns made to look like crossbows, range only duel arena. -Agility courses in real life (For the more fit runescapers, I won't be playing this >.> -REAL smithing or glass blowing. How cool would it be to have your own JAGEX BRONZE DAGGER? (Both are cool as hell, I've done them before.) -Runecrafting. You'd paint a rune to look like one of them in game, stencils provided or you can freehand it. (Not adult only, kids too) -Make your own party hats.
-Merchandise -Capes and hoods. I love capes. I'd buy a cape. (Skills capes, max capes, comp capes) You'd have them look at your account and you can buy whatever you've unlocked. Comp cape particles could be facilitated through micro LED's that run off a small button cattery in the cape. -Game based novelty weapons. I'd definitely buy myself a pair of dragon claws or a whip. (These along with the aforementioned capes would probably be a bit expensive... Available in limited quantities, extras could be sold on Jagex's store.) -Party Pete's afros (I'd buy it)
That's about it for now, I can't really make suggestions on panels or decor. (A life size mithril dragon would be pretty BA though...)