Definately include a washer and dryer.
In my mind, it is false economy to believe you will have a savings in today`s market by not including basic appliances. You want the largest pool to tenants to draw from and once they are there, you need to keep them happy.
If you think that a washer and dryer are expensive, then try a month`s vacancy. In my mind, I wouldn`t even consider a unit without a washer and dryer in a single family (duplex, townhouse, etc) unit. In all my suited SFH`s, before purchasing, I always consider how I can plumb in seperate and private washer and dryers.
For the cost, you will get higher rents, better equity building tenants, less vacancy and more. That`s how I tent to look at the washer/dryer situation.
Best of luck.