5 yr old son shows happiness/excitement through complaints!?

I could take him to Disney, swing by a toy store, grab an ice cream cone and hand him a $20 but my 5 yr old would say hes tired, hot, hungry, bored, exhausted, sweaty ..... the list goes on. He over exaggerates but why can he not just say thanks mom, or I had fun. Even if I ask him, are you having fun? He says, I guess .... WTF !!!! I dont understand !! Any suggestions on what to say? How to react? (other than wanting to grab him and scream about all the time and money I just wasted on him, he'd better be enjoying himself and say thank you HAHAHAH ) I know he is having fun, I can tell he likes what were doing...... I guess I don't need him to say thanks or whatever but if I say anything in reference to what fun were having he immediately complains about something!!!