for a spa, there's
Glen Ivy at the Brea Mall a few miles up the 57 from Anaheim I've been there, :thumbsup::thumbsup:
Downtown Disney is worth visiting once. There are some good eateries (but not very cheap).
The Block of Orange is similar to DD with good shopping/Food options.
The beach is always a good choice (cruising the Newport "boardwalk" is always entertaining).
If you like baseball, you can catch an Angels game.
If you like to iceskate there's a Disney Ice nearby (but that sort of defeats the purpose of coming to SoCal).
You can also get a park multi-day ticket for Dland and spend plenty of time there. If you've never been, you should go at least one day to see the original theme park.
Public trasit in OC sucks, so plan on a rental car if you want to venture away from the DL resort.