I usually register mine for a year, as it is the cheapest option and I am never sure what I will be doing with the domain. If I decide to develop it, depending on the type of website, I may extend the registration.
The longer you register them, the cheaper it is. However, unless you are SURE that you are going to develop it, you should register for 1 year... if you decide to keep it, the next year register it for longer.
I guess because I'm always looking at dev rather than reselling, I sometimes reg for 2 years or more depending on the timescale I'm looking at for building the project (sometimes I know I won't have time for a year or two to get into it properly). Oh and one's linking to my name, I'll just reg for as long as possible as I'll never let go of them.
The only domains I've regged for longer than a year are ones that I have no intention of ever selling. The rest I will reg for a year and have the auto renew option checked.
1 year on anything I'm not sure if I will keep or develop, no sense renewing it for years if you may sell it in a few months, usually 2-3 years on anything that I plan to develop.
I intend to develop all of my names but the option to sell is always there.
IMHO you just end up putting more and more money into the name (for extra years) for little or no added value if you decide to sell.
I'm sure if you did the maximum number of years you'd be able to make the extra money back but for an extra year or two I doubt there'll be much difference.
Also by only owning it for one year, I can buy more domains with the money I've saved.
My longest reg is until the end of '07. That was a name I bought, promptly transferred and got an extra year. Every other name I own expires within 1 year.
the longest for me is 2 years as well as our .ph domain requires it when registering for new ones, otherwise it's usually 1 year for me, my local client required me to register theirs for 5 years advance so i regged it for them.
My 3 letters I register for a minimum of 3 years, usually longer.
Personal sites are registered for 10 years.
Late night registrations or names that I am "unsure" of are 1 year at a time.
Developed sites are a minimum of 2 years to avoid any hypothetical Google penalty.
-Allan :gl: