What i learned about sunscreen ~
higher spf does not mean more coverage or longer protection time. it generally means that you can apply less to get the same amount of coverage. spf 30 will protect you from 95 % of the sun's rays anything higher will up it to about 97% or so.
dermatologists recommend at least 1 shot glass full of sunblock for your entire body. and to use sunblock on your face AND body year round. the sun's rays can penetrate through clothing and even 5 minutes a day to exposed parts of your body can build up to YEARS of exposure.
For the super UV conscious, there are products out there like, UV protective clothing (try SOLUMBRA) , or this product called SUN GUARD that you put in the wash that transforms ur clothes into SPF 30 protective wear (up to 20 washes).

i like the Coppertone's Oil Free Quick Cover Lotion Spray- it goes on cool, is fragrance free, and not oily @ all. too bad that SKIN DEEP COSMETIC SAFETY DATABASE gives it a hazaradous rating (aerosole spray, oxybenzone). the website is definitely worth a look and may change your mind about what type/brand of sunscreen you buy. as for me, i still like the coppertone spray.
So the take home message seems to be do your research and make sure your sunscreen is truly broad spectrum and as chemically safe as you like. ( I will be checking up on my daily moisturizer with SPF !!!) Otherwise, these are a few good ones. Neutrogena dry touch and NO-AD (1/2 the price) got very good reviews from consumer reports. And MEXORYL is an ingrediant that has been shown to be very effective against the sun's rays (esp.UVA). MEXORYL has been around in europe for years, but was recently approved by the FDA. Look for it in Lancome and LaRoche Posay sunscreens.

and
of course ... don't forget your EYES which are BEST protected by 100%
UV (UVA, UVB) blocking sunglasses that will cover your eyes and the
areas around your eyes. this would aid in prevention of things like
wrinkles, cataracts, and macular degeneration, etc. Most plastic
lenses, including contact lenses, only partially block out UV rays.
You can opt to have a clear UV protective coat put on your regular
plastic lenses, or look for contact lenses with enhanced UV blocking
materials.