Hi Chloe,
I returned from this trip 2 weeks ago, had a fantastic time, met some really nice people.
With regard to trips, the Mombassa Full-day City tour + Ngmongo Village doesn't run anymore. The half day Mombassa trip is worth it, you visit the Fruit market (busy) and other places, but basically you see the sites, the Somak guide explains everything about Mombassa, I would suggest if you are intending buying any wood carvings then do so on this trip when you vist the Akamba Co-Operative where all the carvings are done (much cheaper to buy here than in the shops or from traders, plus the carvers get 80% of the price of the items sold)
I went on the Dolphin Dhow and had a great day, yes it is long we left at 6.10am and got back at 7.30pm, but to see dolphins and swim with Sea Turtles who cares how long the day was, some on my tour didn't enjoy this trip, food was basic and the road was bumpy (well last 15km anyway), but well worth it, this trip and the La Marinas Dhow are on the same day so unless you are doing the extension you can't do both, those that went on this trip said they enjoyed it.
Haller Park is now a trip on its own, as Nixon said its just a short trip (its only up the road from the Hotel), it was enjoyable and we got to feed Giraffe and could almost touch a Hippo (it had its head on the wall, just inches from us), I went in morning on the day we flew back so only fed Giraffes, other animals are fed in the afternoons.
Didn't do Fort Jesus Sound and Light, but a few went and enjoyed it (you see Fort Jesus in the daytime on the Half Day Tour).
Others may tell you things and then you will have to make up your mind.
Yes the beggars can be a problem, but the beach traders will leave you alone if you say no a few times.
Oh and just so you know, you won't be spending anytime on the beach, maybe just the odd walk and paddle in the sea, too many beach traders for you to stay too long, plenty of room in the Hotel grounds to sunbathe.
You will have a fantastic holiday, I would have preferred to stay up in the Park at the Lodge the whole time, but we had to come back to Mombassa.
The Somack people were great and the staff at the Lodge were very helpful, the people can't do enough for you, so if you want to know more, just ask.
regards,
Martin