I'm quite happy with the work environment of my current job. But I bet I can earn more money, so I'm interviewing. I'm specifically only applying to companies I'd really like to work for, though - I'm not trying to keep myself afloat.

After all, why not? It's not like you have to take a day or two off to potentially fly out for the on-site these days. It's been years since I played the interview game, so I need to keep my skills sharp. And if I get a better offer at a company I'd like to work for, why not take it? If the offer's not better, I can politely decline.