Personally, Joerillibee, I would recommend the Miramar - have not stayed there myself but have several relatives (all in their 70s/80s) who have and were very impressed with the whole experience. The front terrace is a lovely place to sit and have a coffee, read a book and just soak up the PP atmosphere... Although I haven't seen the bedrooms I have been inside (to use the loo!) and it's always looked very attractive and well kept. I'm told by said relatives that the bedrooms are pleasant too. A lot of the clientele at the Miramar are on the more mature side so they are definitely geared up to their needs.
I think it would be worthwhile paying the extra and getting a front room with a balcony as the views are stunning. I have heard that the rooms at the back are not so nice.
The Daina has always seemed more suited to younger families as they appear to offer more entertainment in the evenings (sometimes quite loud!) - don't know anyone that has stayed here but I don't personally like the rather anonymous airport style of their lounge - this is the only part of the hotel I have actually seen however. The Miramar is more Mallorcan and traditional in decor and atmosphere.