What do you consider high end?
that's a relative term: to someone, a $1,000.00 system is "high end". To someone else, that is entry level and a high end system starts at $5,000.00. To others a high end system starts at $10,000.00.
The bigger question is: what is the wattage output of your amp? If it's in the 100 watt per channel range you could get away with 12 - 14 ga speaker wire. If it's around 50 - 100 watts, 16 - 18, less than 50 go with 20 ga.
Now if you have deep pockets, and some audiofiles swear by it, you can go with oxygen free speaker wire. The copper in OF wire is supposedly produced in an oxygen free environment which means there is no "space" between the copper crystals which is supposed to equal better transmission.
Another rule of thumb is the size of the bass speakers in each speaker. Bass signals are the ones that require a lot of "power" to drive them properly. If you have 6" or smaller bass speakers in each cabinet (bookshelf speakers), then you don't necessarily need thick cables.