<font color=navy>This is my order of preference for the towers:
There are three towers - Marina is to the north where you park and check in at the registration desk; Sierra is to the east, and Bonita is to the south - beyond that is the Paradise Pier Hotel
Sierra facing east - view of Downtown Disney and in the distance Disneyland and California Adventure parks. Best view is Upper Level Resort View (but no guarantee that you will get the Downtown Disney view - you may get the pool view. You can also choose Lower Level Resort View. The concierge lounge is located on the upper floor (maybe 11th floor?), and you have a nice view of the parks. When I can find my online photo I'll post it.
Sierra facing west - view of the Disneyland Hotel landscape, with pool, etc. Again, you have upper & lower level resort/pool views
Marina facing south - this would probably be an upper/lower level resort/pool view, with a view of the pool area. I had a room here many years ago when the pool used to be a marina w/paddle boats.
Bonita facing north - faces the waterfalls and pine trees -- I had a room here, and enjoyed it.
Marina facing north -- some of these rooms are city-standard views - if you have a view of Disneyland, you may get a upper/lower resort view room - not sure. On clear days you can see the mountains - you can also see the Mickey & Friends parking structure, and the city. You may also get a view of Disneyland and the fireworks - but not too sure on that.
Bonita facing south -- view of the city and Paradise Pier Hotel -- I think it's the most generic of views. What I like about the Bonita Tower, though, is that you can park in a little lot next to the tower, and save yourself a walk if you're going to be driving places.
HTH