Drive out of Newtown on rt. 532 South until you get to River Rd. (rt. 32). go left (N) on River Rd. The Delaware River is part of the wild and scenic road system and
River Rd. is a beautiful ride. As far as dinner I suggest the Center Bridge Inn. It is a few miles north of The touristy town of New Hope and you can eat on the outdoor patio overlooking the river. New Hope and Lambertville will be too crowded today and the restaurants are most not worth the money.
You should definately take a ride up to Lambertville. It's more likely only 20 minutes or so. You can get there right off of 95N by getting off at the exit for Route 29. Follow 29 about 7 or so miles into Lambertville. Many restaurant choices there, and lots of fun shopping. I personally like Hamilton and Antons at The Swan. http://www.antons-at-the-swan.com/ http://www.hamiltonsgrillroom.com/
Another pretty ride would be to get off 95 and drive through New Hope, crossing the Delaware in the center of town into Lambertville on the NJ side of the Delaware.
There are numerous bridges that cross the Delaware in that area. If you wanted, you could continue through New Hope on the PA side of the Delaware (beautiful ride), and cross over into NJ up further, then come back into Lambertville. I think you would enjoy the scenery along the PA side of the river, but I personally think the shopping and restaurant choices are a bit better in Lambertville vs New Hope.
If you like Vietnamese...Savor Saigon, recently opened on the Levittown/Langhorne cusp is as good as any Vietnamese food I've eaten outside of SF. You can get there off Route 1 -- from Netown heading south, get off at 213 Maple avenue exit, find Woodbourne Road and take that until you see a sign for H Mart on your right. It is in that little shopping center.
Also...how about Havana is New Hope? Is that still there? It was pretty good when we last went there...