The Lost Dog in Ithaca closed awhile ago. The main location in Binghamton (about 45 minutes southeast; closer to NYC) is still going strong and is recommended. Glenwood Pines is a good choice with kids in tow. There is a good Mexican place in downtown Owego (Las Chicas). I believe you can sit outside and view the mighty Susquehanna River, which is a bonus.
My favorite Binghamton place is actually a neighborhood sports bar that's stuck in the '70s!! The owner has a chef cooking there who produces amazing, non-sports bar food. The whole experience is a trip!! It is called Sach's and is on a side street (Hazel St.) in the north side. My other favorites in the area are Consol's (primarily Italian) and Thai Basil both in Endicott. Burger Mondays ("gourmet" burgers) and the Lost Dog Cafe are a couple of good choices in downtown Binghamton. Escape State Street (also downtown) is a very good lunch-type place that is open late. The Riverwalk Bistro (newly opened downtown) sounds promising but I haven't made it there yet.
In Oneonta, there are a couple of decent places (Autumn Cafe, Ruffino's) on Main Street. Sabatini's on the Rt. 23 strip has good Italian. Stella Luna and The Farmhouse are a couple of other well regarded places that I haven't tried yet. There are also two good coffee houses on Main Street that are worth checking out if you like java.
----- Thai Basil 1 Washington Ave, Endicott, NY 13760
Stella Luna 4 Orangetown Shopping Ctr, Orangeburg, NY 10962
Lost Dog 222 Water St Ste 101, Binghamton, NY 13901
Much has changed since the early '80s in good ole Vestal ... it is now pretty much seven miles of strip malls, etc. The Ground Round is gone ,,, there wasn't one for a few years but it reopened in JC by the mall. The other three restaurants you mentioned are gone. The Vestal Steakhouse (and the big bull) are gone ... I remember the bull got new life elsewhere but I can't remember where. It's nowhere in Greater Binghamton that I'm aware of. I knew the Colonial as I had a dear friend that lived there while attending BU. A part of me was sad to see it go even though it became an eyesore ... the Wendy's is still there as is the Ale House. Pat Mitchell's is not in JC or Vestal anymore ... its in Endicott by the Kmart Plaza and has been there since at least 1993 when I moved here. I am friends with one of the current owners. Vestal Plaza is alive and kicking ... they tore down the Grand Union and built student housing so it is a bustling place. There is a Tullys, a burger chain (5 Guys?) and a good non-chain Thai and a decent Greek place there now. I think the pizza place (Mario's?) is still there also. Champion Outlet is gone as is the steak house (the Bull's Head). There is a place (Grande's ... different than the one mentioned in my earlier post) in that plaza now. The parkway doesn't really have any Italian places now but there are plenty still around in the area.
A good Italian place on Harry L Drive (in the area you are staying) is Cacciatore's. A non-chain steak place in that area is Christie's. Food is good but I find it a little on the expensive side. There are a couple of diners on Main St. in JC where you can get a decent, standard breakfast. Crepe Heaven (Main St in Binghamton) is good and has great coffee and their desserts look good (haven't tried them). They have both savory and dessert crepes. Worth checking out IMHO. I recommend Joey's and Consol's as well. There is a little coffee shop across from Joey's (can't remember the name) that has good coffee but the hours are sporadic. I am not a fan of Whole in the Wall; mediocre food and too pricy. Grande's (around the corner from Whole in the Wall on Vestal Ave.) has decent food including pizza.
----- Main St Cafe 6 N Main St, New City, NY 10956
Crepe Heaven 217 Main St Ste 1, Binghamton, NY 13905