We went on the bus this time, from Alicante airport to Benidorm, this is how it works.
You come out of terminal 1 and walk straight across the road up a slight ramp, the bus stop to Benidorm is clearly signed, there was a lady next to the stop selling tickets, and she spoke English and was helpful.
It was 8 euros each, the bus runs every hour, on the hour, during the day, it only stops twice and takes just under an hour, the first stop is the main bus terminal at the top of av. europa and the second is at the bottom of av. europa, the junction with calle gerona, near to the rock star bar.
(right next to a taxi rank, which is handy)
coming back, buses run every hour, on the hour, during the day and it's the same bus stop where it drops you off, you pay on the bus, there is no longer a ticket booth nearby. It's the same fare going back - 8 euros.
so, all in all, it went very smoothly and for some people it might be the best way, it depends on circumstances. At 16 Euro return, it may be the cheapest and quickest way of doing it.
Possible drawbacks - if you buy the tickets at the bus stop or on the bus, there may be a remote chance that the bus may be full up, although you can avoid this by booking tickets online, it doesn't allow for late flights etc, so it's not worth the risk. Personally it wouldn't worry me, the worst thing is you catch the next bus, and they are probably not full up that often.
There were a few rowdy people on the bus, but it was just high spirits really, nothing nasty.
Link below that takes you to the bus timetable.
http://www.alsa.es/portal/site/Alsa?portal.alsa.request.locale=en_GB