The first thing I'd advise is to leave the N96 well alone. It's fine for some lucky owners, awful for the other 95% with bad build quality and unstable firmware amongst the favourite complaints.
The N95 8GB may lack expandable memory, but it's still one of the best Nokias of recent years.
Thinking of your requirements, I would advise you hold out for the Nokia N97. It will achieve everything you want, but it also has physical buttons for when you and the touchscreen don't get along. It should be a great halfway house.
The downside, as mentioned previously, is the size. But I think this is a compromise worth making to get a more modern phone with the features you want. And with the storage of the N97, the Sat Nav abilities and the physical keyboard, it should be the only device you need to carry. Just wear loose jeans....