What backpack should I get?

I'm going on a couple of excursions this summer and I am looking into getting a new backpack. I'm going to Glacier Nat'l Park in July with some friends and we may be going on a couple of overnight trips. Also, I'm going to Colorado for a couple of concerts and will need to be able to carry a tent and sleeping bag, plus the essentials. I'm looking for something that I can take onto a plane and possibly use for my luggage. Thanks for any help!