You realise most people are just going to come and give you their breed of dog, don't you? 
Except me 
No, honestly I do not own a greyhound. I foster them and they are wonderful, wonderful, calm dogs. Who do fold up small and are very good and gentle with all people, including children. They don't need anywhere near as much exercise as you'd think, but equally will walk for miles if that is what you want. They detest 'weather'. Mild and dry is the only kind of weather they cope well with, anything else has them heading for their sofa (they will get on the furniture, you cannot stop this. Keeping a greyhound, or indeed any sighthound, off of the furniture, should be a crime imo)
They don't shed a lot and they're not really very demanding. Two 20 minute walks a day and they'll spend the rest of their day upside down on your sofa legs in the air.
Whippets are very similar, but smaller and ime, slightly more excitable than a Grey, although that could just be the ones I have met. They're still good dogs for families, though.
Whenever I hear spaniel I immediately think "hard work, excessive exercise, training and grooming needs" although to be perfectly fair I have never owned or looked after any kind of spaniel, this is just the impression I get of the ones in the park.