I dunno sullyfish. I think you have to have some sort of chemistry going on before going on a date.
I'm with the others that say don't make excuses, just tell him you're not interested in dating right now.
Back in high school, I had a guy friend, Bob. We were always going to the movies, out to eat etc. Just as friends.
A couple of times a friend of his, Jim came along with us.
While we were all together somewhere, Jim asked me if I wanted to go to a movie that weekend. I said sure. Bob had to clue me in later that Jim had asked me on a date.
No way! I just thought we were going to the movies, like Bob and I always did.
I didn't know how to get out of it, and for me it was an extremely ackward evening. Ever after that whenever I saw Jim I felt ackward.
If you're not interested, you're not interested.
I guess I take a date more seriously than other people do.