You don't have "ho" written on your forehead, and you'll soon get used to going into hotels. People are in and out of hotels all day, especially the bigger ones. They're staying there, visiting people who are staying there, working (as staff!), going to the bar, the gym, function rooms, the loo (well I do that). The fact that you're a woman walking into a hotel is one of the least remarkable things imaginable.
Nice hotels are likely to have people who'll ask if you need help, but that's just customer service because people are in and out all day for all the above mentioned reasons. Usually it's easy to work out where you're going so you can say no thankyou, but I've asked to be directed to rooms in big confusing hotels and that's been fine too.
On my way to my first job I was stopped by a nosey receptionist in a budget hotel who insisted on calling my client and asking him to come down, except all she said to him was that I was there, so after we'd both waited for a while she called again and then said I should go up. That was just someone doing her job badly and nothing like it has happened again in my five years of working, and even so it was only an annoyance.
There's some hints for looking confident in hotels here: http://www.saafe.info/main/index.php?topic=41.0