Varnish is quite 'passe' with the advent of the 'modern'
acrylic/urethanes. Two products that will last typically at least 5
years: "Honey Teak" and "Smith&Co. 5 yr. Clear". If you do at least
one major 'overhaul' you may get more years. I'm into 6 years and still
looks good. These 'almost' look as good as varnish, can be
power-buffed back to brilliance, but typicaly need a quick overcoat of
clear once yearly. They are catalysed 2 part base plus 2 part clear
and can be totally applied in one long day (4-5 coats). The 'secret' to
make tham last is to put on HEAVY base coats. The longer they are
exposed to sun the lighter they get. They are expensive but when you
amortize over 5+ years are really cheap overall .... and much less work
than all the 'others'. Dont use them on Iroko or other teak
'imitations'. For recoating just rub the finish with a 3M purple pad
and apply with a soft artist's brush.
Honey Teak is available from www.signaturefinish.com.
I use Honey teak with extra applied clear coats and then flat sand
(2000 grit) and then hand rub with rottenstone for a mirror finish that
would make a brand new Hinckley blush with envy.

I abhor Cetol and Cetol 'Light; as they both hide the wood grain (and
look like **** and ****-light).

Absolutely NOTHING will look as good as varnish, but it *always* loses
adhesion and eventually lifts.