i recommend a nice restaurant party -- many have a private party room, or they can set up a private area. if you do a nice brunch on a sunday, you can save a lot of dough - get a pre fixe meal and serve wine and beer. the only place that comes recommended to me from my sources in your area is Jazz Trio's - they have a great menu starting at about $15 per person, depending on what kind of food you order. hopefully you love jazz (you can ask who will be performing or check out the calendar on the website). the place is classsy, elegant, but not stuffy. he can wear a suit if he wishes, or just a nice dress shirt & slacks.http://www.triossb.com/trios-banquets-fulldoc.cfm
if you wish, i can design great postcard invites, thank-you magnets as a favor, a "happy birthday & welcome" sign in poster for your guests to sign in and wish him well, that comes with a matching pen. all you need to do is send me a couple of photos and his favorite colors/hobby. I can get you all of this for about $200 and send you pdf's prior to for your approval.
designate a pal to take photos, and for $30 more, I can put together a soft-covered coffee table book. (you can send me the SD card - i'll fix the photos and make the book, having it sent directly to you.)
Best of luck and do let me know how you do and if I can help you further.