
We booked 2 weeks at Voyager in Mombasa and booked our safari separately with a local Kenyan company. We spent 3 nights (4 days) at Tsavo East, West & Amboseli. It was the perfect arrangement for us because it meant we could take the safari when we chose to (we had it bang in the middle of our holiday) as I didn't want to go straight out on safari on landing in Kenya like many of the packages booked in the UK do. Plus, we were able to book to have exclusive use of our safari jeep...means you don't have to fight for window seats or jostle around for the best views of the wildlife, and you can dictate how long you stop at any time.
I reckon you could get it cheaper booking camps directly or using one of the Kenyan companies...there are many excellent local safari companies who use exactly the same camps as the UK tour operators and you can tailor make your safari to suit yourselves. You're getting married in September, yes? I just had a quick look using random September dates on First Choice website and Diani Beach resort is around £950 per person for 7 nights (and £1240 per person for 2 weeks). So, that means trailfinders are pricing at around £3k+ for safari...that sounds like a lot to me, even for the luxury camps. I'd advise you to shop around a bit first before committing yourselves.
Lots of people at our hotel at been out to Maasai Mara and had a brilliant safari experience. We plan to go back to Kenya in future to do the Mara and Samburu

We had a fantastic safari but I'd love to try to catch the migration next time...you're going at just about the right time to stand a chance of catching it

OH wants to climb Kilimanjaro too

. Personally, I was happy just to see it from the ground!
Opportunity knocks...
Temptation kicks down the door