souq waqif at night is a must see, then if you like Corniche as its just walking distance.  Katara fine, the Pearl just so-so unless your brother like the kind of place- all about boutiques n restaurants by the harbour.

if you like to explore middle east style, if your brother is an adventurer or like nature, you can call tour agent to go for a day dessert tour, maybe 3-7pm, Inland sea is a very nice place to go that u will get dessert and beach!  Or.. you go to Film City in Dukhan, it was Transformer's shooting place.