I went to Tenerife about three years ago with a bunch of girls, loved it, I was a bit reluctant as I heard bad reports but this really depends on where you stay. Playa de las americas is the main (rowdy) resort, don't get me wrong, I wouldn't avoid it like the plague, really depends also what time of year you go, we went in May and this was perfect, I'd imagine it gets very rowdy in peak months. We stayed in Los Cristianos, quick taxi ride from las americas, we stayed in apartments at the time but there was one hotel that stuck out to me on our way to the beach every day, it's one of the iberostar hotels, you can see it here at
If I was ever going back to Tenerife I would stay here, hotel is devine, we went in a few nights to have a nose around and it was fab, google it though, I'm not sure what the reports would be like but it's only a two minute walk from the beach and this was the nicest beach ever. Luxurious sunbeds, mcdonalds on the beach if that's of interest, lovely beach bars with waiter service to your sunbed and not that expensive. I remeber to eat out at night was so cheap in comparison to Ireland, it was three years ago so not sure what it's like now but my sister had been there about six years ago and she didn't remember it changing too much. The area of Los Cristianos was also been redeveloped at the time we were there so again I'm not sure how that turned out but for this hotel and the beach alone, I would def go back...........best of luck with the trip