Mounting at 25' gives you better signal strength, enough that I would strongly recommend it over the lower level. You'll also want to avoind aiming into trees and buildings.
When you have a mix of UHF and VHF signals, an antenna designed to both bands is best. In your case, a UHF only antenna will not provide reliable reception of the available signals.
Combining a UHF only antenna with a VHF-only antenna is inexpensive and easy to do. You simply need a UVSJ.
http://www.radioshack.com/product/in...ductId=2103923,
http://www.solidsignal.com/pview.asp...nna-%28UVSJ%29. This method can be used to your advantage in the case of the signals to the NW. An Antennas Direct 91XG , roof mounted in the clear, pointed toward the NW (about 334° compass) gives you access to eight or so UHF signals most of which will carry more than one virtual channel. Then, point an Antennacraft Y10713 at WSIU (about 51°). connect each antenna to the UVSJ and the output of the combiner to an Antennas Direct CPA-19 preamplifier. The output of the preamp is then cabled to the TV or splitter if more than one is to be connected.
The signals to the SE would need to be treated separately. A Winegard HD7698P equipped with a CPA-19 would be my choice. Pointed toward 132°, you would expect reception of five more stations. I would consider adding a rotator to this antenna if I had an interest in DX. This antenna would cable separately from the first system. I would use a separate external tuner at the TVs that I ran this secondary feed to.
http://forum.tvfool.com/showthread.php?t=2882