Founder and Naming Director of Brighter Naming, offering naming and branding consulting worldwide. Former Intnl VP Sales and Marketing and tech guru - no naming project or subject too technical or scientific. Tracking all the naming trends. If you want to pick the brain of a naming and branding guru, who really gets the gist of scientific, industrial, engineering and software products, as well as financial, real estate and consumer products, then call me and I will give you more than your money's worth.
The problem you have, as is so common with many of these answers, is that they try to jump right to the problem. Wrong. It is like looking for a job. In reality you are looking for 100 places to send your resume to get 20 interviews to get 3 offers so you can pick one. So you need a methodology that puts lots of ideas in the hat and then you narrow it down through a funnel process. Marketing 101.. See Marketing Textbook from profs at Kellog School (NorthWestern).
When push comes to shove, it is not about the domain at all. It is about the trademark... and he who owns the trademark wins legally. Doesn't even have to be same products or services - if they are in same industry they may be covered by same registered or even unregistered common law rights. And no one can register or own a generic name anyway. Get yourself a unique name and build your own brand, on a .com or .net or .org or .biz or soon .hotel or .travel or .xyz or .corp or .shop or .web.... all of these will be here within a year... so unless it is about you (me) don't go there.
What if I don't like Melissa - or the bad guys discover that is the magic keyword? Surely I can pick my own name? Ted, Frank, Melinda? So company name should be different - like modernsteward or MagicButler.com (better still.. it is for sale for a small fee from Brighter Naming)
Cold cold calling is stupid and takes forever. Either set up dummy site or info and share it then ask for feedback. Quickest way (that my son did to great success) setup in a coffee shop and put an ad on Craig's list and offer to pay $10 for anyone who will come by and see your demo and give feedback. In one day and hundred dollars you will have your answer more than you can believe.
Only the super big guys can handle multiple brands! And they have separate operations teams handling each one. Humans need to be fully immersed in a brand to do it right, and few can handle many on the same day. Plus how do you cross promote? Doesn't matter if it is online or offline. Notice Amazon is one brand for all they do.
As one of my industry colleagues said: If you think all the good domains are taken, you don't understand branding. Think about naming your agency, not describing it. We easily find 100 free .com domains on every naming project.. and often a lot more. With names that sound like they should be in the dictionary.
And yes, soon all the new domains will be here...like .web or .shop or .online or... BUT BUT trademark rules will apply even more than before - and trademark rules govern domain rules. So please make sure the trademarks are clear before you pay for any domains. By this time next year it will be very acceptable to have a non .com domain name. May even be cool to be a .buzz or a .cool!