I started DMing for the first time this year in an effort to get my group to switch to Pathfinder - complete success.
We started with "Hollow's Last Hope" - seemed to have a good mix of delve & RPing. And it's already in 3.5, if that's what you're starting with.
Went right into "Crown of the Kobald King" which was a huge hit.
If you're looking for something for a longer-term campaign, you might want to consider some of the older 3.5 adventure paths, like Rune Lords.