I don't have a specific recommendation, but I do buy the oils and mix in a few drops to freshen the fragrance. My grandmother gave me a potpourri when I was just a little girl that was kept in a covered container. I open it up on occasion and it still maintains that rose fragrance, even though it's probably 50 years old already. It had no wood chips but full of tiny rose buds.

I have a nice set of oils too, including rose. I just need the potpourri to drop them on! That's the kind I am looking for!

You might look on etsy....

I no longer know a good source for premade potpourri, but if you can get good rose petals next season, look for recipes for moist rose potpourri. The moist potpourris are more highly scented and last for years. You keep them in a jar with a tight-fitting lid and just open it long enough to scent the room. Here's a typical recipe:

http://www.care2.com/greenliving/three-potpourris-formula.html