Ringworld's not the best book to start with with Niven, I agree. It was pretty slow in parts (though I did very much enjoy the Kzin and Puppeteer characters). Niven is very much "hard" sci-fi, and that book in particular was more interested with setting out -how- the Ringworld could actually function then in telling a story. It's sequels are actually a bit better, IMO, cause he gets past that somewhat.
Another thing about Ringworld is that it's pretty much the culmination of the entire Known Space series, which I think is in total now almost 20 novels and short story collections. Ringworld comes at the end of his "future history", and there's a lot of good little nuances that you miss out if you haven't read the backdrop.
The way I would start with Niven's solo works would basically be to start going chronologically into the Known Space Universe. Try starting with World of Ptaavs, Protector, A Gift From Earth, and almost any of the short stories surrounding Gil "The Arm" Hamilton. That way, you get a better idea of how we got -there- (Ringworld) from -here- (Protector, in particular, is key for understanding what went on in Ringworld). The short story collection "Tales of Known Space" intersperses stories from throughout the entire 1000+ year future history, and thus gives a very very good general overview.
Qwinn
Is that the one in which Niven introduces us to thrintun and whitefood?
What was the name of that scientifically adept people who developed the whitefood to be resistant to the psychomanipulative abilities of the thrintun?
I'll probably think of it before you reply.