We naturally all have a bias of how we approach improving our web sites (Information Architects through an IA lens, programmers from a technical perspective, etc), but we should all occassionally be looking broadly at what is required for success of your web site. I would also advocate that someone (the product manager) should always be looking broadly at site success.

As always, I advocate starting with the vision of what you are attempting to do. This could be your vision for an upcoming site revamp/migration, or your long-term vision.

After you define your vision, you can then help to combat you and your team's biases by:

1. List out the various factors that will lead to meeting your vision.
2. Evaluating where you are, right now, against those factors.
3. Roughly determining how strong you need to be in each area.
4. Concentrate on the deltas, in particular those that have a wide gap.

So instead of diving into one particular area with a tactical view of your problems (for instance, a deep engagment improving the graphic design of a site), you can concentrate on those that will derive the most value. Also, hopefully this will focus discussions so that you are always going to just enough complexity that will meet your needs.

One way of representing this would be in a graph, highlighting a) the "ultimate" / maximum maturity / most complexity / most impressive / most Amazon-like / fantasy, b) current level, and c) the level required for your vision. See the example below, which highlights those areas where you are meeting/exceeding the capabilities toward your vision (in green) and those that require work (in red). In this example, your design level is exceeding what's required toward your goal (which would be good, but on the other hand might be an area where you could spend less). The widest gap in the example is around setting a shared vision, so perhaps should receive the most attention.