I love running in Blaise, though it was better before they tarmacced all the paths. There is a nice mix of flats, hills and grass, and you can always end up on the golf course. It's also good for hill sessions as there is a fantastic range of gradients and surfaces and steps etc.
Only issue is if you don't like dogs.
Ashton Court is fine but be careful of stray golf balls.
Have you tried going out to Almondsbury, Pilning etc and running around the country lanes? I love doing that for variety. You do need to drive out there though.
Where else? City centre is ok - out along the river and round but it does get a bit dull - always easy for a lunchtime run though.
I woulnd't venture on the Towpath by the Portway, as it can be a bit dodgy. Certainly don't think of doing it on your own.
I'll keep thining.
LRC