Double is mandatory on the 2551 hand, were my hearts more concentrated kx, KQT9x,Qxxxx,x I would bid 3H (although even then, double could be much better)... what to do over 3D, 3H, or 3S is trickier.. I would bid 4D or 4H... 3S might be a hand stuck for a bid 5233 which doesnt fancy 3D - I would pass that I think. On the other hand a reopening double isn't marvelous - but you sort of have to do it playing take out doubles. Double in both cases keeps all contracts - ESP including 3Cx, 3N, 3S, and 4D as possible contracts, 3H can get a disgusting result (esp if pard 5152 and does not have the values for 4 forcing diamonds)