I'm a fan of Butter's Foundation Flawless base coat. It dries quick and has a beige tint that neutralizes the splotchy appearance and texture of my unpainted nails. In fact, I like it so much that I occasionally apply only this base coat to my nails. Two thin coats are enough to give my nails a polished look.

re: protecting your nails--you should start moisturizing your nails if you aren't already doing so. If you're painting (and therefore stripping nail polish) often, then your nails are likely dehydrated and in need of a good oil massage therapy session. Here's a good guide to moisturizing your nails. Good luck!