I got this route, again, off www.routeyou.com, and it took me slightly further north than last time, through the hearts of Moorsel, Sterrebeek and Kraainem before hitting the ring at Meiser rather than Diamant. It was a more pleasant route in general, apart from one slightly scary tunnel of trees which was a tough climb uphill on a dark mud track, as I worried that I might encounter someone else zooming down in the opposite direction. (I didn't; just a man with a big dog.) It came to a hair under 25 km rather than the 23 km of the more direct route, but I did it slightly faster than last time - 1h 25m rather than 1h 30m.
Given my general level of fitness (I put my back out quite badly a month ago) I think 25 km is enough for one day. But I might try and do it again before the summer break.
(Comparison of routes: today and 2010, in Google format.)