HIGHLY recommend booking lodging asap. October is harvest season and things are already booking up.
The wedding is in Glen Ellen which is about 15 minutes north of Sonoma Plaza. There are hotels in Sonoma Plaza, but we highly recommended finding an Airbnb in the area. There are quite a few choices and pricing is usually more affordable.
It is only about a 30 minute drive.
Our answer here is both. Of course overall, we love Napa Valley a little more than Sonoma, but there is plenty of good wine in both places. Napa is more well known for the bold reds while Sonoma has quite a few choices of Chardonnays and Pinot Noirs. Sonoma also has a bit more of a laid back vibe and can be less expensive. When in doubt, just google or better yet....ask Antonio!