That is a hard question. How much work needs to be done to update your kitchen? And, how bad of shape is your existing siding? Will you be installing new vinyl siding or fiber cement? These are all important questions.
If you are after best return on investment, be sure to check out the 2011 Cost vs Value report at http://www.gettum.com/cost-vs-value-2011/remodel-cost-vs-value-2011.htm which will give you relative value of projects based on your specific area.