I managed to get 600 points in one trip to DOH. I think BA have sales on in the summer so this may well be the on the cards. DOH is very nice and I'd especially recomment the Ritz-Carlton there if you were thinking of staying for a few days.
Basically I got a LHR - BAH I fare in the sale last year for about £950 and then booked the BAH - DOH in F separately. I checked through my bags to the final destination both ways. I got 240 points for the LHR - BAH - LHR and 360 for the BAH - DOH - BAH. Silver in one go!
If you want to do this without staying, leave LHR at 10.30 on Saturday morning and you can be back in London at around 6.30 on Sunday morning
