I really like the Ascend 170SE speakers, but I'm a little confused how you think these will fit in a suitcase.
(sorry for the bad pic, my camera is dying)
The box they came in to protect them was quite large . I wouldn't put any speaker in a suitcase without the foam that they orignally shipped it. I'm not sure I would do it even then. They can easily be damaged, and you wouldn't have any insurance on them.
But, if you really want to do this, I don't think you can do any better for the $$ than the Ascends 170SE. I've heard good things about the XL-S speakers. I've had the SVS speakers in my house, and while they were good for $200, I wasn't as impressed as most and they weren't my first choice.