The laws around here MA, NH & VT that I'm familiar with do NOT prohibit CCW in a bar or restaurant. They do prohibit being "under the influence" of alcohol while possessing a firearm however.
Law aside, everyone has to understand him/herself, their tolerance of alcohol, the sort of place they are going, how they react to situations, etc. All of this needs to be taken in consideration if you are a responsible gun owner. So a good answer for one person may not work well for another person. This is definitely grist for the YMMV mill . . . and it gets discussed here every month or two with a new thread.
Personally:
- I don't go to bars and haven't done so since I was 23 yo (and the last 18 months of this was dating my Wife and it was strictly a piano bar, very low key) and I didn't own any firearms back then (a very long time ago). Before I met my Wife I occasionally went to only one disco/bar while I was in college. It was was run by the mafia (not speculation, but fact confirmed to me one day by the bookkeeper's Wife) and I only nursed 1-2 drinks for the entire evening there.
- I do go to restaurants and may have A DRINK with dinner, and I may be carrying. I don't consider this to be an issue. [A handful of times, I've been seated at the bar for dinner due to long wait for a table vs. we can seat/serve you now at the bar. Again not an issue.]
- I avoid problems, stay away from sketchy areas and would not intercede in anything I saw happen that didn't personally threaten myself, my Wife or those I'm with. If possible, I will make a safe exit and call in the heavy artillery.