Another possibility could be to implement a "rotating" roulette like Frontline offers a different battlefield that changes each day. Each day offers a different tier of roulettes (one day is CT roulette, next day is Mhach roulette, etc.), and the ilevel requirement changes accordingly based on the top raid in the tier.

Of course, this has the obvious downside that people trying to queue for specific raids can only easily get a party together every third day... but would greatly improve the wait time on those days.

Not sure if it would be better or worse than the current system.