We have hosted two parties at Club Longwood, the smaller of the two venues run by Longwood Events. The other venue, which is in the same building, is a full size ballroom. Both are located very conveniently in the Longwood Towers complex directly across the street from the Longwood stop on the D branch of the Green Line. (They also run the State Room at 60 State Street.)
The Aptekers ran a restaurant called Veronique at the Club Longwood location. It was very good. About 3 years ago, they switched to events only.
The room is exquisite - look at the website - all fine panelling, with carved details. The food is excellent, at the level of the finer restaurants in the city, and the presentation is creative and immaculate. Service is always excellent. The staff is easy to work with in planning your event. When you have committed to them, you will be invited to tastings which are frankly over-the-top explosions of almost all they offer for food and hospitality.
We have held parties for about 100 and about 70 in the Club Longwood space.
Because the site is on the T and has a parking garage, it is very easy to use for anyone living in the immediate Boston vicinity. We had numerous guests from out of town and the local hotel - the Marriott in Brookline - ran a shuttle to and from the event for free.