Weather has little to do with it for me. I book months in ahead and if it is bad just take it and ride anyway.
I've done a few -
Kielder Marathon series
Selkirk Weekend (Sportive and MTB marathon)
Virgin Money Cyclone
Price has put me off. I've done plenty of them before and for the price of an event I can just drive somewhere and go for a ride.
What they offer is often poor value for money in my eyes. I'd rather not pay for the free bottle, t-shirt, millions of feed stations that I don't use (just water for me would be fine) etc.
Ones I have done that I won't be doing again include
Whinlatter - as it was pretty expensive for what it was and I don't like queueing for sinlgetrack.
Kielder 100 - just for this year. I've done it twice and after finishing last year spent £100's fixing my bike.
New ones -
3 Peaks - one of the more expensive but it is unique and I've never had a go before.
Local XC series - cheap and local so done in an evening
Local CX series - cheap and local so done in an evening
Local Time trials - cheap and local so done in an evening
Sportive wise I've bought a GPS and don't need the "support" that goes with an event as I can quite happily go off and ride centuries without arrows, feed stations, photographers etc. HAving said that a few of the more interesting ones like Fred Whitton and Etape Caledonia may be on my list for next year.
The market is pretty saturated and all sprotives seem pretty similar. So unless you offer something unique then I probably won't bother. It would be good to see more hard courses. 100miles is fairly standard riding wise so it would be good to see some longer (150m+) ones or ones that really pack in the hills.
Same for the mtb stuff. I love the Selkirk course and like to support the Kielder race series but they are 4.5hr and 3 hr rides respectively (for me). I'd like to see more hard races which are longer. 50-75miles off road