What an exciting business you have! Since you did not indicate your budget, I'm going to assume you'd like to do this as cost-consciously as possible. First, see if you can connect with anyone else in your area who may have a well-established firm handling this kind of luxury service, as they may be able to outsource some of their business to you right away.

Since you are from America you may also be able to "mine" your own connections for leads. Getting a recommendation from someone is a terrific way to get your foot in the door and the sales process started.

Another relatively inexpensive way to get in front of the the right demographics is online advertising - perhaps through Google Adwords. You set the price so you can spend as much (or little) as you like. Another step up would be to take an online button ad on some sites of luxury magazines in the US - like Conde Nast Traveler, or other upscale publications (look into custom publications like Greenwich Polo Magazine).

Next, I'd suggest surfing the net to seek out luxury travel specialists in select cities in the US (say New York, Los Angeles, Chicago, Dallas, Boston) to reach travel agencies that may be interested in your services for some of their clients. You can also go directly to well-known global companies (from different industries) like IBM, GE, and Bayer. Through research on the internet, email the prospects in each group (seek out contacts in corporate travel departments of global firms) and introduce yourself with an overview of your services. Follow up with phone calls to all the leads you contacted by email and then send some professionally designed collateral materials (either via e-mail as a pdf. and a hard copy via DHL or Fed Ex.)

Before you contact anyone though, make sure you have a clear sense of exactly what services you will offer and the fees for each. You might want to Google "personal travel assistants"  or "luxury travel concierge services" also to see who else pops up. You can research your competitors wherever they may be - just get a handle on the services they offer, and their pricing.

Best of luck!