yeah, I agree with jhunger, if you can go in and play them (ukulele or guitar) do so even if you are not that familiar with these instruments. even better would be to take a friend with you who already plays.
I have a couple of concert ukes and they are almost too small to play (for my hands). my tenor is a little better. I have a cuatro tuned like a uke that is between a tenor uke and small guitar and it is the perfect size for a uke for me!
I agree the Lanikai are good ukes. I own a couple of Lunas and they are OK but they tend to look very cool and not play quite as well! my tenor is a Riptide from Boulder Creek and it is a really nice uke.
now if you really wanna be confused I might suggest trying a tenor guitar! Four strings, smaller than a regular guitar, nice sound and kinda unique cause most folks do not have one! I am planning to add one to my collection this year. Prolly gonna get the Blueridge BR-40TCE which is their newest model with built in pickup.