I don't mind massive weapons being a niche weapon, but it would be nice if they weren't quite so niche as they currently are. Mushkilla pointed out in this topic that you are pretty much always better off equipping a fighter with two daggers over a massive weapon and making them a little more useful might encourage diversity, especially in gangs like Goliaths.
As I see it there are basically two different paths to making them more useful.
Firstly you could give them an extra bonus to offset their negatives, something that reflects the huge nature of massive weapons. Rules such as making them ignore parries, or giving a bonus when they charge or just during the first round of each combat, such as conferring a -1 attack dice penalty on opponents or +1 combat score bonus.
The other option would be to go in the opposite direction, for massive weapons to represent a much wider variety of two-handed weapons, like bastard swords which aren't particularly unwieldly as the "always lose draws" rule suggests. For example you could allow them to be used with one-hand at a reduced Strength and with an Initiative penalty while using them two-handed would not confer a penalty, thus giving them a bit of versatility.
I'm quite torn on which to favour myself. I don't think the first option makes a lot of sense fluff-wise, since why would opponents fear dealing with a massive weapon yet not suffer a similar effect from a power fist? The second option would open up more modelling opportunities but you also lose what gives massive weapons character, they would become merely "slightly bigger weapons" rather than "massive weapons".
I'm curious to know which direction you guys prefer and if you have any specific house rules for them yourself that you favour?