I was a VAP at two top SLACs right out of grad school. My first position (which lasted two years) was chosen based on geography at the time and the desire to increase my teaching experience. The second (for one year) was because I didn't get a T-T job.
These were largely great experiences. I felt pretty integrated into the departments (minus service requirements!) and my teaching load was not excessive (generally 2-2 with thesis advising). I made connections, had more time to get papers out/published, got to live in a couple cool parts of the country, got a great letter of rec from one of the department chairs, and greatly boosted my teaching experience. I landed my dream T-T job at the end of all of this (an R2, I guess), which I started with my classes pretty much prepped already. It's not like adjuncting. You really can feel a part of things, and are paid pretty decently - at least where I was.
Clearly, I think the VAP is a wise move if you're not bound by geography. And if you want to ultimately be at a SLAC, it could be a smarter move than a postdoc, with better pay to boot..