26 works the best right now in summer your gonna be packing alot of shirts the bigger the better 7 days is a long time in the winter you take even more clothes. I usually always check my bag on the first and last day travel especially in the summer finding over head bins is tough I would rather relax check it at the counter and not worry, I've had my bags not make it once not because of checking it in at the counter but because of trying to carry it on the plane and not having any room for it, The airline couldnt get it on in time to make the push back or they already closed the cargo bins. Just dont be like that X F.O out of MKE that has the flashing wheels on his overnight it really scream I'M GAY! we all know who you are steven