I used to be a sales associate and would wear heels ALL the time.. the highest I've gone for a work day there was 4 inches. I DO NOT KNOW WHY haha. My feet are HURT now. Now I work an office job and can afford to do that, but I commute to work via public transportation and so I decided to wear flats while traveling and then slip the heels on at work. The highest I would or could ever do anywhere is 4'', but I like a heel a little under 3'' best.
Basically, if you are not on your feet very much, have fun and wear the heels.. start with a kitten heel or even in the middle with a 2 to 2.75 heel. Also, if you travel like me, bring some flats in your bag!