My commute uses a chunk of the BG trail between U Village and Fremont. Mornings aren't bad, but evenings can be life threatening. I try to keep my speed to barely faster than the walking speed when going through the high traffic areas, but I frequently get passed by racers down in the aero bars trying to set their personal best TT time. I'm often tempted to stick my pump in their spokes.
For training rides, I mostly avoid the MUTs. I use Lake City Way instead of the BG trail heading north, and Willows Rd is a good alternative to the SVT.
All those folks with their strollers and trike riding kids and dogs and such may be annoying, but the fact is that they have the right of way and they have just as much right to use the trail as those on a bike.