Costa Brava and area

You can't do all of those in a day, especially meaning the visit to Montserrat. Montserrat is not on the way north and is a little over an hour to get there (it's a 20 minute drive up the mountain alone). And while one can easily see the site in an hour, that is still 3 hours total. Girona is about an hour and half drive. And depending on when and where you get the car, you could face traffic around Barcelona. If you leave off Montserrat, you could do some or all of the rest of it. Keep in mind that some of the roads along the coast are twisty mountain roads, so actual travel times are more than the actual mileage.

I've read mixed reviews on Montserrat. Is it a must see or do without. I know it's always a matter of personal taste, but I'm always interested in others point of view. Mary

We like Montserrat, but a consideration is how weather effects the day you plan to visit. Montserrat is conveniently accessed via metro and train from Barcelona.
You have alot of driving time planned, but the real question is "what are you trying to accomplish?" A long scenic ride?

Montserrat would not be nice in poor weather or poor visibility. The monastery itself is rather plain IMO and not very old (the original was mostly destroyed by Napoleon and the rest by Franco). But the craggy peaks of the mountain (the name means serrated mountain) are pretty cool. And on a good day there are great views. It's great for hiking if you enjoy that and they have relatively easy hikes you can take to scenic vistas.

Thanks for responding, I never gave the weather much thought. When I picture this trip every day is sunny and clear. I guess I should have a few "Plan B's"

I would say to start with the section that most interests you, take your time, and allow the plan to change if you run out of time, especially given the advice above.