Wednesday 23 July 2008 3.00pm
Agree with Zac that running east from Tower Bridge avoids crowds and is very atmospheric.
For the distance you're looking at, also consider running east on south side of Tower Bridge along river to St Mary's Rotherhithe (hello SE16!), loop back into King's Stairs Gardens, cross Jamaica Road
to run around Southwark Park - then retrace steps to the river again.
Pretty much all river or green run with plenty of space!