How much money to bring for 1 week travel

Mike,

General expenses in LV can be quite low.  Meals can be had easily for 5-10LVL (often even with a beer involved.) Some of the great tourist options may cost you up to 15LVL per person, and some of the nicer restaurants outside of the tourist zone are similarily priced.  There are all options from street kebab, to oyster bar  and sushi restaurant.

There is lot's to buy for gifts etc.  I recommend the local textiles (wool garments and socks,) and of course amber and silver jewelry and ceramics.  You can get gifts for loved ones from 5LVL to 100LVL.  A good tip is to go and look for things in the large downtown market (tirgus) before buying from a vendor on the street.  I also recommend that you look for the old Grandma knitting in front o her wares

Many tourist attractions in Riga are free, and others are in the 2-4LVL range - including the art gallery, and museums.
Opera's and Classical Music are quite popular and are cheaper than I expected (coming from Canada).  Tickets can be had for < 10LVL.

As you have a car, and a hotel, I won't discuss that much, but bus transit is ~0.50LVL, and hostels start at 12LVL while hotels can be found in the 30LVL range easily.
These prices are lower in other cities, and there are plenty of AirBNB options for cheaper.
Guest houses (bnb) are quite common (Viesu Nams) and are also quite affordable and often very nice places.

The night life in Riga is great.  Simply walking around and having a beer in one of the downtown squares is easy, and affordable (2LVL per beer/wine.)  Nightclubs are of course more expensive, but not unreasonable.
There is an old US Embassy warning about some scams in nightclubs, but sticking to the tourist guidelines makes things more than safe.

Overall - I'd say for the kind of traveler who has his hotel and car booked already, 40LVL per diem is an upper safe limit.

J