I think what you have to do is move to a country that doesn't have the
trademark dispute problem, namely, most places other than Germany and
Britain.
http://en.wikipedia.org/wiki/Gmail has the reasons why.
Seriously, I think that may be the only way to do what you say you want:
which is to have @ gmail appear at the top of your account when you login to
Gmail. As long as you login to Gmail from either of those countries,
@ googlemail will appear at the top of your account when you login to Gmail.
But that is something only you see, isn't it?
Anyone can send mail to you at @ gmail.com and it will be delivered to you
even though your account is @ googlemail.com. So, you can tell people your
address is @ gmail.com and it will work just fine. And, if you run an email
client program on your computer (such as Outlook or Thunderbird) rather than
using Gmail's web interface for sending mail, most of them allow you to
configure the settings so that you can change the "from" address to
@ gmail.com. But this will not change what appears at the top of your
account when you login to Gmail.
At one time it was possible to do that (to change the "from" address to your
@ gmail.com equivalent) from the Settings in Gmail, which affects mail you
send while you are logged in to Gmail on the web interface (that is, not
using an email client program running on your PC); but it seems Gmail
doesn't let you do that anymore for this specific case of trying to get
around the gmail.com/googlemail.com issue. My guess is the lawyers made
them do that.
Andy