IMO, you could make a compliment without seeming hitting on or lame.

I sometimes say to women I like "Wow, you have a special spark in your eyes" or "It's like you're radiating light" or "Your smile nourish my soul" or "Your blouse's color is so pretty", etc. (in a friendly and not creepy way, of course ;-). I just notice something that's not obvious but it's part of her persona.

It's not sexual or directly related to their beauty, thus it's not awkward for them. They may sense I like them, and it's OK. At the same time, it's not so forward to need a rejection: if they're interested they can go on, if they are not they just smile and say thanks.

I say most women appreciate those kind of compliments, because they feel appreciated and - at the same time - not being hit on or sexualized.