If you use a honed travertine you will have less problems with wear. It will still wear just as much (and scratch as much) as a polished travertine, you just won't see it because of the honed finish.
You can use Hydrex for a sealer Here is a link:
http://www.defusco.com/Glues:-Epoxy,-Polyester,-etc.-Hydrex-Sealer/c82_502/p2095/TENAX-IMPREGNATOR-AND-SEALER---1-LITER/product_info.htmlIf you want to give the stone the wet look you can use Ager, but then when you scratch it the scratch will be lighter than the rest of the stone and therefore more noticeable. Here is the Ager sealer:
http://www.defusco.com/Glues:-Epoxy,-Polyester,-etc.-Ager-Sealer/c82_503/p1437/AGER---1-LITER/product_info.htmlI like the Hydrex much better for travertine floors, and use it myself on my travertine. Seal it before you grout it and it will also act as a grout release, preventing your grout from adhering to the stone (as long as it is a filled travertine) as well as preventing the grout from staining the travertine.
Glad to be of service,
Mark