The Emirates A380 suite, is a must do. I'm not sure how much longer it will be viable to put a shower in a non-private plane for.

Personally I can't see many more in the future due to the cost to transport the water around and also the amount of space the shower rooms take up.

It seems to be working for Emirates though, they offer a slightly smaller First Class cabin than their key competitors, but offer the shower. Personally I think the Suite is large enough and like the shower, however I would like to try the double bed on Singapore Airlines if you travel with a partner in the middle cabins ;-)

I've also had some of the best wine in Emirates First (think the LHR route especially).