I think that sounds fair. If the photos are being taken at the same venue as the ceremony, then the bar is only a hold over place until the reception so it's only three locations.
You don't even have to make the bar a formal arrangement; you could have the ceremony officiant announce the idea before you arrive at the ceremony so people know there are informal options. Some people may not wish to go to a bar, they might choose to drive around, go home, stay at the park and chat, etc. It's only an hour and a half between the two which will go quickly. Plus, if you don't make it formal, you don't have to pay for the drinks...

If you're looking at a restaurant for your reception venue, I think you'll be hard pressed to find one that opens earlier.