What's your budget and when are you going?

Bilbao has a an interesting old town (casco viejo) which is neat to walk around.

If the weather is nice, you might want to take the funicular to Mount Artxanda. There's a little park on top, and it's a good view of the town. I think there are a few restaurants up there, too (though we didn't eat there)

On our last trip, we walked over to the Guggenheim to check out the grounds, the Jeff Koons puppy in front and the building; we didn't go inside. We then walked down the Gran Via, a main boulevard that cuts through the city, and explored some of the streets around Calles Diputacion and Ledesma. There are a lot of pedestrian streets here with tons of shops and bars, and it's fun to just poke around. We really liked this area in the evening, when it became a big street party. Definitely stop at the bar La Vina del Ensanche for some mouth-watering ham pintxos.

I took a taxi to the airport both times I was in Bilbao. The hotel called for us. We stayed once at the Conde Duque (a Best Western, directly on the river) and a second time at Ibis Bilbao Centro Hotel. Both were simple but comfortable and clean, and we paid less than $100/night for a double. Plus, it was an easy walk from both to get to the old town and to the pedestrian streets I mentioned. We also stayed in the Old Town once, but I wouldn't recommend the hotel, and I preferred the other locations better.

Where you choose to stay will depend on your budget. Bilbao has a number of excellent hotels in all price ranges. You might take a look at booking.com to see what's available on the day you'll be there. Most hotels in the center of the city are only about a 15 minute taxi ride away from the airport.

The city has a number of fine art museums, including the Guggenheim Bilbao and the Bilbao Fine Arts Museum (Bilboko Arte Ederren Museoa), but since you're not really into art, you can take a walk through the Casco Viejo, the old city, join the crowd and have some pintxos before lunch. Be sure to visit the newly renovated market. If you have the time, you can continue your exploration of the city with a walk through the Ensanche or through modern Bilbao. Take the cable car up to Monte Artxanda and see the city from above. It's quite a sight. You can go shopping along the busy Gran Vía or head out to Getxo on the metro to see Abra bay and Puerto Viejo.

I hope you get to enjoy your brief stay in Bilbao.

jmc that is what I want to spend is around $100. Did you like one of the two hotels better then the other? That park sounds interesting. My wife and I both kind of like walking around seeing architecture and stopping at bars/restaruants and having a drink? How much was the taxi to the airport? about how long did it take?

Thanks,

I also had one night in Bilbao and got a good internet rate on the Barcelo Nervion.
http://www.barcelo.com/BarceloHotels/en_GB/hotels/Spain/Bilbao/hotel-barcelo-nervion/general-description.aspx
I cared less about charm and more about convenience, with only one night and an early flight like you. I don't recall the specifics about the taxi, but it was stress-free.
I liked the area for walking along the river between the casco viejo (which I was not really fond of after enjoying San Sebastian's) and the Guggenheim.

I would give the Conde Duque the slight edge only b/c I liked the area a bit more, but really both were fine and you can't beat the price. For one night I think I would choose the Ibis. It was spotless and there's a taxi stand right out front.

If I recall, the taxi was around 20-25e, and it took less than a half hour (we also had an early morning flight). The Bilbao airport is small and efficient. You don't need to get there hours in advance.

thanks Robert appreciate the advice. I think we will do the cable car and then just walk around. Would you recomend staying in the old city or by the muesem probably want to spend around $100 on a sunday night in september

The cheap way to get to the airport is on Bizkaibus A3247, running from downtown up a bridge and into a tunnel that leads to the modern airport. However, according to the airport website, the bus doesn't start until 5:25 a.m. Your hotel should know if that would be enough time to make your flight. http://www.aena-aeropuertos.es/csee/Satellite/Aeropuerto-Bilbao/en/Page/1237554477328//
As to accommodations, location is not a major concern. The downtown -- which is really down, nestled between the steep banks of the river -- is easy to walk and has plenty of public transport including a subway.