not sure if this is a question or a statement...
response to statement
indeed it should be a simple process but sometimes it isnt.
response to question
keep the old site running as long as possible.
set up new site on test server. get them to review on the test server. clients are hardly ever happy first time around and if you are messing with their "live" site during this process they'll be even less happy, particularly if it goes down.
when the client is happy transfer from test server to the real server. do it overnight when traffic flow is at its lowest. that way the client has little to no downtime from old to new site.
The client is happy with the design, and I've been testing on a server so far. All of the design questions are answered, now it's just to make sure that it doesn't lose it's SEO or anything when the new site goes up.
Here is the checklist of things I'd like to do/do again before it goes live:
o 404 page
o http:// to www redirect
o meta descriptions
o proofreading/spelling recheck
o sitemap
o index with google
o backup of old site and new sites
o Check links
o Validation
o SEO/semantics writing
o Analytics
o Google search relevance
o Optimize HTML/CSS
Is there anything I'm forgetting?