You may want to post this question over on the marathonguide.com message board. Address it to Zeke. Zeke may have some connection to the BAA, and seems to have a lot of knowlege regarding all aspects of the Boston Marathon.
Another option is to post over on the Spring Marathon Training team's group message board. There are bound to be some folks who've had family cheering them on. I've run the race, but have no idea from a spectator view point as I came alone.
A good point to cheer the runners would be at one of those points along commonwealth avenue in Newton. Best is to take the tube from downtown. Once you get to Brookline, and specially close to the finish, on Boylston street, is way too crowded to see anything.
There is lots of good info here, thanks all of you! Here is what Zeke from MarathonGuide.com had to say to my first inquiry. I like, "sea of Humanity." It reminds me of a sea of manatees. I hope it's sunny!
Sure thing. The challenge for spectators at Boston is that it's a point-to-point course. The start in Hopkinton is very crowded race day morning and state troopers limit vehicle access from all directions. The finish at Copley Square in Boston is also a sea of humanity. However, it is very possible to see a particular runner 3 times along the course if you know the back roads to drive. Q: what do you think your finish time will be? That'll influence the number of times they'll be able to successfully leapfrog the route.
You will be a sub-3 Max. So, no way they will be able to see you along the course more than once. I still would recommend they would wait somewhere at Newton hills and cheer for you, which is where you will need it the most.
A map of the whole course is found at the PDF link below. Your family will be using RT9 to travel east and west in parallel with the marathon route. The Natick location can be found by driving RT27 SOUTH from RT9 (look for them on the left side of the road). The Newton location can be found by driving Walnut Street NORTH from RT9 (where they'll be standing on the right side).
And also, this wonderfully informative post from W. Allan Sharrett on the Spring Marathon training group forum:
My wife has enjoyed two very positive Boston spectator experiences over the last two years. A few observations: 1) the expo where you pick up your number/shirt is open to everyone, and is a great event, with all sorts of entertainment, merchandise, exhibits. 2) if you're going to the lasagne dinner on Sun night (included in the cost of registration for you), you can purchase dinner tickets for those with you. Our experience with this meal has been good. 3) you should get passes on the "T", Boston's subway system. It can get all of you to various points of interest in the Boston area at reasonable rates and with pretty good service. 4) on race day, my wife found the best viewing places to be at the 17 mile mark, and at the finish. One of the lines on the "T" has a stop at the 16.7 (or 8) mile mark, so she was able to get there, see me come by, then get back on the train and arrive at the finish in time to see me. Leave plenty early in the morning to get there, as tons of people have this same strategy. Also, the earlier you get there the better your chances of seeing the hotshots race by. It is well to establish a place where you'll be standing, some distance downcourse from the T stop - there are literally thousands of runners and spectators, and it helps greatly in being able to spot someone if both of you are looking for each other at a designated place. We selected the 17 mile marker itself, just downcourse from the T station, and found that it worked well. You need to look for them on the right (as opposed to left) side of the road, as crossing the street is impossible there. Regarding the finish area, there is a long straightaway leading to the finish, and Betsy has been able to get a spot where she could see me, and I her, both years. Last year, she was at the last intersection on the course, and I saw her as I turned the corner onto the final straightaway. 5) access to runners after they cross the finish line is restricted, and family has to wait for them to exit at designated points. This is very well marked, however, and it's easy to spot your runner, as the meeting points are signed conspicuously and alphabetically. 6) if you come from a Christian faith tradition, there is a wonderful Mass on Sunday morning at Our Lady of Victories Catholic Church. The church is within walking distance of all the downtown hotels; the service is geared specifically to marathoners; and everyone wears their shirts/jackets, and is made to feel welcome (neither my wife nor I are Catholic, and we were welcomed with open arms). 7) make meal reservations in advance for the nights you will be in Boston. The town is mobbed, so reservations are essential. 8) they should sign up to receive text messages telling them when you've crossed certain points on the course. You'll get an e-mail in the coming weeks telling about this. It enables them to follow your progress electronically, and to estimate about when you'll reach certain points. I think the points are 10K, 1/2 mar., 30K, and the finish. There may be one other point, as well, maybe 20K. 9) finally, family not able to attend can follow your progress on the BAA website, which posts more split times than these. Last year, my wife was on the phone talking to my daughter in England who was reading split times from the computer! If you have any questions, please don't hesitate to contact me. I'm sure this will be a terrific experience, both for you and your family members.