David Sparks in Smashing Magazine gives a nice overview of decision making models in web development in his post (June, 23 2010):
The most interesting parts to review are the models themselves, all intended to help you get a more settled, structured decision.
For example, the SHEL model (Software, Hardware, Environment, Liveware) will remind you that when you choose your target hardware (PC, smartphone, etc.), this affects other aspects of your solution, such as the user’s environment, and will impact on the end user’s experience and capabilities.
DODAR (Diagnose, Options, Decide, Assign, Review) speaks mostly about the process of decision making itself.
And there is much more.
Anyhow – this is worth the reading (link again) and whatever you choose eventually, don’t be shy to think and evaluate again, as long as it doesn’t hold you back on your plans and time-lines…