This year I am staying in a bungalow on the French side of the Pyrenees near Fois(Fos) and will want to day-trip over to Spain or maybe even make a run to Barcelona. Any suggestions of destinations near the border?

I don't know very well that area, it looks Barcelona is a bit far for a day trip, isn't it?
The roads in mountains have lot of curves...
I think I've heard about Ripoll, Vic, La Seu D'Urgell if you want to look for information about htis places, also Vall d'Aran and Aigües Tortes are beautiful although they're farther.

If you don't have a car, Barcelona will be too far.
Around the Pyrenees area there are wonderful places, like the Nuria valley (near Pigcerda, in the border), where a ride in a rack train will lift you to a 2000m valley with a sanctuary home of the virgin of Nuria.
It's an alpine scennery just under the shadow of the mighty Puigmal peak (just under 3000m)

The road that runs from Perpignan, FR to Prades and up through the Pyrenees to Andorra then down into the Noguerra Palaressa and Segre River valleys, is amazing. Stay in Sort, a wonderful, magical village, whose name means "Lucky" in Catala. Buy a lottery ticket there! I can't say enough how friendly the people were.