Thank you for your question. Your friend may obtain a UK visa by applying on-line. I strongly recommend she applies online before going to the US, so that, by the time she is there, she can already go to the visa application center to collect her biometric information. However, it is also possible to apply (still on-line, the Consulate in Atlanta does not take or process applications directly) while in the US, and pay for expedited service, in which case, particularly if she is there for a few weeks, she may also go to a visa application center (which is in fact a Department of Homeland Security facility, working on the charge of the UK government) in Atlanta. The web application process is described here, while the specific information for applying from the US is here.
The Schengen visa is more complicated, in that she needs to decide on a 'main country', i.e. the particular country where she wishes to apply for the visa. This is because the 'Schengen visa' is in fact a national visa of a Schengen country which, because there are normally no border controls in the Schengen area, is by treaty defined as being valid in all Schengen countries.
Her decision should be based on the following considerations:
1. The list of Schengen countries (which is the EU member states, minus the UK, Ireland, Romania, Bulgaria and Croatia; but plus Iceland, Switzerland, Liechtenstein and Norway);
2. Which country she will enter first;
3. Where she wishes to stay longer;
4. If there are any connections (friends or relatives, or business connections) in any particular country.
I should also add that it would be best to pick a country which has a representation in Atlanta (see the list here), and which is better at bureaucracy.
My tip: top choices would be France, Belgium, The Netherlands, Luxembourg, with the first two having Consulates General (which means they have the power, in principle, to process visas), as opposed to the other two which have Honorary Consulates (which means that they have to send the application somewhere else).
Tell me which country she would like, and I can reply with the application process within this same question.
I hope that my answer was useful and look forward to your rating now, or after the clarification answer.
Dr I L Vlad