Blue- Do you have a weekend full day to see something scenic? If so do you know what weekend? I'd suggest VT for the most scenic and flow trails around here. The top of Burke at KT is pretty phenomenal but that's about a 3 hour drive each way, KT is tough to beat though, something like 100 miles of singletrack, some lift service machine built trails and some great stuff that descends about 2200 feet off the top of the hill- roughly a 20ish minute downhill on some great flowy hand built trails. If it happens that you're here 9/7 weekend I'll be up in the north country somewhere, either KT or the White Mountains of NH, another place for great views.
Immediately around metro Boston you've got the Fells (good view of the skyline off the skyline trail lookout, you can't ride skyline trail on a bike but you can take a fireroad to this lookout point). The fells isn't super techy but it's not flow either, it's kind of in the middle. That is going to be the closest MTB trails to Boston, about 5ish miles from the FiDi.
If you want to see the best trails, and some great views, head up 128 to either exit 17, 15, or 14. All have great trails and some awesome views, mainly of landscape like the ocean and rolling NE style hills.
Close to Boston you also have Landlocked, Needham Town Forest, Hale Reservation/Satans Kingdom, Lynn Woods (one of the most technical rated trail systems in the country), Vietnam, Fells (mentioned above), Wompatuck, Willowdale (mentioned above), Pisgah, Callahan, and if you get a bit further out the options keep expanding.
I've ridden Vegas a bunch of times Bootleg, the stuff out by Red Rock Canyon. You're not really going to find views like that around here, we just don't have that kind of vert that close to the city. The climbs close to Boston tend to be short spurts here and there but add them all up and you can easily link together 1000+ climbing, just doesn't come quite as easy as heading up the trails to the top of bootleg. Also the trails here aren't marked nearly as well, since there are trees everywhere it's best to go with someone who knows the area, almost all of these places have group rides going most weekends and quite a few weekdays.
Anyways, hope that helps. Can't wait to go back to bootleg again, great stuff there!