I used 1.5 oz medium toast oak chips in a 5 gal batch. Toasted them in a pan to get the oils aromatics going and added to the secondary. I believe the recommended contact time was like a minimum of 4 weeks, it said on the package that I don't have anymore. I left it in contact for approximately 6 weeks while the beer aged.
In fact, it is still aging: bourbon+oak+vanilla+porter+1.103 SG (way overshot conversion from AG to extract) + nearly 1 year bottle ageing=excellent winter warmer.
All in all, I'd recommend the oak if that's your thing. But I'd caution on the low amount, 1.5 oz is good, but I've had extended ageing, so it depends on what you're going for I think.