Thanks for your interesting questions, not easy to answer actually.
First of all I think we both love these 2 places because we feel "home" there, and this can be explained just after years of stays, beautiful summers and memories (I came the st time when I was 4 month old and I'm 44, my mother used to come when she was a kid, and my kids do and bring their friends).
Then for beaches I think they are very similar, I used to come to Rimini with my classmates on Sundays when we went t school, simply beacuse it was closer to Bologna, but at a certain point I suggested to move to Riccione, which I knew very well, simply because the beach was closer to the station, but they immediately loved it and never proposed to go to Rimini again.
If I compare Riccione with Rimini I take into consideration mainly the part of the town on the beach, Rimini centre is for me to compare with other cities, the beautiful small ones of Emilia Romagna, like Ferrara and Ravenna.
So as for the sea part, I really think Riccione is much better than Rimini: you have the most beautiful shops of the Riviera (together with Milano Marittima probably) and they are not for Eastern buyers only, I always buy there in July with the sales, and many people do (and there are still top brand shops like Iceberg, Armani and Dolce and Gabbana), a large pedestrian area, green and beautiful on the sea, with bars, restaurants and no cars, a beautiful porto with nice restaurants as well, all the fancy discos for young people, Oltremare and Acquafan for kids and teenagers, Terme for elder people, you see Gabicce and this gives you something natural to see among the many hotels of all the riviera adriatica; there's the friday market where you can find fabulous vintage long elegant dresses for 5-50 € , what you can ask more to it?
But if it's many years you are coming you should know that Riccione is considered the best place together with Milano Marittima of the Adriatic coast, many famous people if they come for a few days in riviera stay here, it's from the 60S that it's a place for the Italian (and sometimes international too) jet-set (did you know that the famous football player Pelè chosed Riccione for his honeymoon?).
It became a sort of "mith" for young people in the late 80s, when Radio DJ started to work from here in summer (and they still do every day in Viale Ceccarini), actually I did not like it very much in that period because it was too crowded, and also now I never stay in August for the same reason, I like mainly June and July and after a few years of it I hate "La notte Rosa" for the same reason,
As for the kind of tourism, there are all kind of people, Russians of course (but also people from Arabians countries), gays probably ( I usually don't ask), young people, families, elder people (my mum's aunt has come here until she was 86, then she died, and she loved Riccione a lot, she loved to walk early in the morning on the beach to the porto, and to dress up at night to go out and see many beautiful people in their best clothes)
Of course you don't come to Riccione for the culture, but I live in Bologna inside the culture every day so I don't care if for a month I just sunbath, walk, talk, read (this is culture in any case), go to the restaurants and do some shopping.
I don't wnat to convince anybody to come if it's not the right place for them, I would like to have less people sometimes in July too, but when I read a post I ask to myself what they are actually looking for, depending on the period in which they travel, the age of people and on what they are focusing on, for these reasons I suggest a place or another.
The average price for a sunbed is around € 8, but if you stay more days you spend less (like 15 for 2 days and so on).
Edited: 1:37 pm, May 07, 2013