dizzy.. there are places you can go to that are far less touristy.
of course in Tenerife, many head off to LC or PDLA and yes, they are very touristy..what about the North? and also LG is a little quieter that the 2 main places but does still sometimes get busy.
In Lanza, most peeople head to PDC, which is very touristy.. but you could try CT or PB, which are not so busy.. or even travel further North to Orzola, to the west where you will find La Sanat and El Famara.
IN GC, PR is the busiest place, but head further west to see real GC, i would thoroughly recommend Mogan. It is called Little Venice coz of all its little bridges and inland canals etc. It is the most south westerly point in the whole of the canaries and i found it the least touristy place i have ever been to out of all the canary islands.
La Gomera is just really quiet and you get there via Tenerife ( but if you are like me you would be bored after a few hours

luckily we only visited for the day)
At the end of the day, a holiday is what you make of it and everywhere you go in any country has some elements of tourism in it.. thats why we are there!