how long is 'a while'? 2 years? 4 years? 8 years?
how much are you willing to spend?
Anyway had a look at the mobos you suggested, it appears that there is only a $40 difference between the 2. I'd say get the 750i even though there are hardly any difference besides the fact the 680 can't use more than 800mhz ram. 750 has better overclocking capabilities too (slightly).
Neither motherboard has particularly high FSB restricting overclocking capabilities. Also neither support DDR3 which I believe would become far cheaper soon.
Sorry but I can't provide you with any recommendations atm, haven't been keeping up with all the new mobos.