How about 8x Boost for 1 hour @ 10 gems?
I would like to see the option to choose between a "standard" boost of 4x for 2 hours and an 8x boost for 1 hour.
This would give advanced players an extra opportunity to spend money in a sensible way.
I would definitely use gems more frequently if I could build a huge army (on boost) in 15 minutes... but as it is now, I have to wait 27 minutes for AQ40 to recover (1:48 non-boosted!)... Cooking 5+ golems takes at least 33 minutes (boosted) and my spell factory takes 30-35 minutes boosted.
I see this as a win/win opportunity for both players and SuperCell. Sometimes a player doesn't have 2 hours to devote to the game but they might perhaps have 1 hour to boost. The 4x speed is great for lower-level players and for cooking small armies like Barch and BAM. But hot dang wouldn't it be fun to be able to practice war raids every ~15 minutes?
Please SuperCell, consider offering your loyal TH10 players an 8x boost for 1 hour for 10 gems. We'll thank you with increased gem usage.