If you're over 6' tall you definitely need to pay attention to the dimensions of hydration packs. Many of them are quite short - many with the "waist" strap going around my ribs. I have an Osprey Raptor 10 that is awesome. The construction is killer, it's surprisingly light and has tons of clever features.
I've been using the Palos since last year. I find I have to run it around my navel to be comfortable when riding. Overall I really like it. Just enough room for a couple of basic things (tool, pump, levers, quicklink, phone/keys/wallet, triangle bandage). Overall it's a great solution for most of my Shore rides. I could see 1.5L not being enough on hotter days.