If you get in touch with any of the greyhound agencies, you more than likely will be able to go and visit a house full of greyhounds to see if they really are a breed for you. That's what happened with us - we went into a house of 5 greys - and all 5 had a different personality, but more importantly you can see their interactions first hand and ask all the questions you want. That's how our first meeting went and we stuck around the house for 2 hours before walking away and said - awh yea!
Aside from suggesting a greyhound, I do think that there are breeds out there for every person. Obviously don't get a husky or a border collie unless you are prepared to make it work and exercise every waking moment you have or else it will destroy your house. Don't get a dog just because it looks nice or cute, you should really get a dog that fits you and your lifestyle because it won't be fair to either you or the dog if you guys don't get along. If you want a lazy dog - a greyhound is great. If you want something with more energy to go biking or hiking with, then a higher energy sporting dog might be better for you. There are lots of breed selector quizzes out there for you to help you out, but I know some are inaccurate.
We originally looked at Whippets before looking at Greyhounds because I was worried a grey would be too big in the home, but now we have 2. I also bought the annual Dogs in Canada book regarding dog breeds and read about alot of the dogs I thought would be best for me. It's education and research that is important.
Best of luck with it all. Don't take it lightly, dog ownership is a great responsibility. We have to drop our boys off somewhere to be cared for if we are going to be away for an extended period of time (8 hours or more). This sucks for weddings, or going to visit people far away, etc. I'm sure this sounds like common sense, but sometimes people are just blinded by getting a dog because they want a dog, and really don't think things completely through. It's not fair for the dog if you won't be home 20 hours in the day, etc., and plenty live for a long time.....life expectancy of our greys are 14 years - a long time for a large breed.
I know one of the biggest guilt factors for hubby is getting geared up to go for a ride on the bike and both dogs come up to him wagging tails and he has to tell them they can't come. We still haven't found helmets that will fit, or a sidecar......