How to proceed with domain switch AND url change

[TruvoDirectories]

Hi,

in a few weeks we'll do a major change on our website. This involves over 1.5 million pages indexed in Google driving substantial amount of our traffic.

Basically we have 2 types of changes:

1. subdomain switches to domain:
   ex. product.company.com will become www.product.com
   for this we know how to manage DNS and Apache rules
2. different url patterns, basically replacing ugly urls by pretty urls
   for this we have advanced 301-mapping rules set up

Here is the question - what is best way to proceed with these 2 changes in order to preserve rankings and organic traffic:

1. Do both changes simultaneously?
2. First do url changes, than the domain switch

Can you please share your thoughts?

[elephantseo]

I would do both at the same time that way if you take any hit/penalty for the changes it is only once. You may also want to submit a change of address through webmaster tools for the subdomain switch.

[perfectweb]

As long as you have your 301 redirections setup correctly and your sitemaps updated appropriately, I don't think there will be any additional penalty for making both changes at the same time.