Tuesday seems s bit hectic. By the time you get to Leverick, settle in get the car and do all the etceras I don't think your going to feel like taking the boat back out to go to BEYC/Saba. At least I wouldn't.

Saturday: even in a PC it's going to take you awhile to get back to the marina from Great Harbor. Personally I prefer a short ride home that last morning. I like Great Harbor, Peter for the last night as it's a short jaunt across the channel.

Edited to add: looks like fun trip. When are you heading down? And just realized you're not going back to RT so not quite right across the channel.