Have you looked at any of the Osprey packs? Theyre a little pricey but high quality. Another suggestion is what I decided to go with for my equipment needs. I only have a small under-seat bag and don't want to go to panniers (yet) and sometimes need a little more room but I don't think my DaKine skate pack is form fitting and (I guess) "technical" enough for anything over a mile. I picked up a Hydrapak Big Sur from Bonktown. Its pretty small, but I usually don't run into much hydration issues so I pulled the bladder and use that as the main compartment. Doubles the amount of stuff I can carry. You obviously need something larger, but look at larger hydration packs like the H.O.S.S., they're usually pretty tough and if you don't need the bladder pull it and use that compartment for more carrying capacity!