DCs are really just a long day on the bike (and IMHO, that's a good thing). You start early (e.g. 5AM or so) and finish late (e.g. 8PM or so).
After completing a windy, hilly century, I had a friend announce:
"Now if we were Vic, we'd turn around and do that all over again."
But it really isn't like that. It's hard to explain, but there when you start a DC, you've got it in your mind that you'll be out for a good long while, and the first 100 miles actually goes rather quickly. Mentally, it is nothing at all like doing a century and having someone tell you you've got to go and do it all over again.
By all means, go for it!