I'm having a great time in Shanghai.
have a good/great/wonderful time (in)
I wish you have a great time during your summer holiday in Hawaii.
They are all very kind and I had a great time last night.
A:Hey,Michelle,this is my friend James.He's visiting Shanghai from New York.
B:Hi James.Nice to meet you.So,uh,are you visiting for business or pleasure?
A:Well,actually a little of both.I'm meeting some business contacts but I'm also taking some Mandarin classes.
B:That's cool.How's it going?
A:Well,I'm finding the classes pretty tough actually,but I'm having a great time in Shanghai.It's really an amazing city.
B:It sure it.Are you staying for long?
A:Only two weeks unfortunately.I wish I could stay longer but.
B:Well,listen,if you need someone to show you the sights then just call me.I'm having a little get-together at my new apartment next week.So you can drop by then if you have time then.
A:That sounds great.I'd love to.Let me take down your number,Michelle.