Hi Nikola,
Both 35' and 50' offer significant improvement in available signal to receive. I would install at 50' if possible, if not 35'.
The Hampton Roads signals benefit the most from this increase in antenna height. WVBT FOX with these greater antenna heights improves significantly. At 35' FOX reception is possible, at 50' reception should be well into the reliable category.
At 50' with the greater signal strength, my antenna recommendations I'd keep the same. Orientate both antennas to magnetic heading 24. This is due to some of the Hampton Roads signals being in 2-edge conditions. Purchase RCA preamp TVPRAMP1R. Run DB8e coax to UHF input, run Y10713 coax to VHF input. Run single lead of coax down to splitter. Before you connect your coax lead to the splitter, put preamp inserter inline. Preamp inserter then will connect to your splitter. Run coax to each TV.
To get 50 above ground, a telescoping mast may be an option.
http://www.3starinc.com/rohn_h50_tel...enna_mast.html
Now, the Greenville signals. The number of signals from that market doesn't really increase. NBC and CBS do improve. There are two ways to approach this. The first, with a preamp on the DB8e and Y10713, you may receive Greenville stations off the back. If that doesn't work, a second dedicated antenna and separate lead may be appropriate.
Good luck in your installation!