First, you may have to spend $$$ to establish trademark rights globally.
Next, you may have to spend $$$ to defend those rights globally.
It might actually be cheaper to register the interesting name in the top gTLDs and the ccTLDs where the name is likely to deployed.
Cost of lawyers, trademark registrations, etc. = $$$$$+
Cost of registering domain in top TLDs = $200+/-
I also wouldn't go spending all the money on your clever/catchy/brandable domain unless/until you actually have proven the financial viability of the website/Web service. For that purpose you might run your initial test on a "throw away" domain - which you redirect to your brand domain(s) once you prove the financial viability of the idea.
Hi friednly4chat and also welcome to WebmasterWorld.
I agree with Webwork on this, but would also like to point out that if you are so concerned about the domain extensions, not registering them now could cost more in the long run if they get bought up by domain resellers who, basically, hold them for ransom. This happened to a client of mine who, through oversight, let a domain expire. A company snatched it up and then wanted $10,000.00USD to sell it back to them. They weren't going to pay and simply got another domain name.