I definitely recommend the Nigerians. We currently live on less than one acre in an apartment attached to my grandmothers house and my parents. So not only do we have 8 human adults, but also 5 ND goats, 40 chickens, 2 ducks, 1 German Shepherd, 1 Holland Lop, 3 adult cats and 3 kittens, with plenty of room to spare. At one time we had 9 Shetland sheep 2 large goats and 1 Nigerian (before I bought my 5) here. You can do a LOT on one acre! Happily this summer only the goats, 5 chickens and maybe 1 cat will be going with my husband and I to the cabin we're building in the middle of nowhere on 4 acres of our own, but access to much much more.
My 5 ND's are currently kept in a 12x12 pen (and I could easily keep more) that I clean out once a month (during the summer, not able to in winter!) they also go for a browse walk at least once a day during the summer, and when it's warm out in the winter I let them out to get more exercise then their pen allows.
MAKE SURE you get well bred Nigerian Dwarf Goats. I'm really surprised when I read about the others on this threads experience with ND's as far as milking. Here in Alaska the well bred Nigies easily sustain the 305 day lactation that they need for testing, and some of the breeders were commenting on how they had difficulty drying up their does because they were still producing a lot. Many still produce a quart a day up till the 305 day point. But this is also coming from Alaska's top breeders that have put thousands of dollars into buying some of the best ND lines in the country and bringing them to AK. Lines such as Piddlin' Acres, Rosashar'n, TX Twin Creeks, Jobi, and Gaymor. That list is just what one breeder has brought up. Other breeders have brought up more lines.
Here is a link for you to see how much milk is expected from a top line breeder, so you can know if your dealing with good dairy lines or not.
I have only had my girls for 6 months, and their milk had already been slowed way down before I got them so between that and my pulling them off of grain I eventually had to dry them up after about 6 months from giving birth because I was getting so little. But this time around things will be different. 3 of my girls in the past gave around 1 and 1/2 gallons a day combined, and the other girl that I added to my herd, that has the smallest udder, gives a quart a day at top production.
I cannot stress how important it is that you research research research the lines you want. I didn't research my goats very well until after I had bought them and I believe now that I will be breeding two lines in my herd, one that is rather meaty, but also produces lots of milk, and another that I hope to work in a lot of milk, and they will have good dairy conformation and will be good for me to sell my kids to those who want to show their goats.
Also MAKE SURE they have been tested free of CAE, Johne's, and Brucellosis (sp) and ask if all abscesses have been tested for CL. My goats had been tested 1 1/2 years before I bought them so I thought they would be fine, but now I am dealing with the possibility of them having caught Johne's during the last six months before I bought them because they had been moved to a new property. So if the have been moved to a new property since their last testing insist it be done again before you buy. Otherwise you could be putting hundreds of dollars into animals that you may have to cull.
My ND's are an absolute delight. The only time I have not cared for having goats was before my husband built a sturdy pen out of rough planks from his saw mill. Once my goats figured out that they cannot get out, they don't even try anymore. They are VERY quiet, except for when they need something (missing something in their diet) or are in heat, except for one doe that likes to start announcing about an hour from milking time that she is ready to be milked.
They eat very little, and even with the high prices that I pay for everything here in AK my goats will cost me barely over $1000 a year, and that was back when I had 9 that I did that figuring. I also figured that if they give as much milk as they have in the past then I will be paying $1 a gallon for milk. 2 gallons of milk a day will be plenty to make all my dairy products from, plus have some left over to give to my family. So in the long run, my goats are actually saving me money, because I was/am paying $7 a gallon for raw cow's milk from a cow share, plus plenty for the only cheeses I can handle, which are raw or high quality.
Here is a link to show you what a well bred ND should look like.
If you look into goats that are ADGA registered, ADGA has this WONDERUL pedigree search so that you can find out who your goats are related to (and thus avoid in breeding, which I highly recommend for anyone who is new to goats). It also will tell you if there is ADGA award winning goats in their lineage, if they have had any registered offspring etc. I have put this tool to MUCH use in the 6 months that I have had my goats.
http://www.adgagenetics.org/
Happy goat hunting!
**edited to fix some of my horrible grammar and add some links.**
Of course I think Nigerians are great for small spaces and love the rich milk they produce. They are easy to handle and have great personalities. Whatever decision you make that will work for your situation, welcome to the goat world!
Bee and I are also members, and we manage to do lots on one acre! I have up to 2 goats at a time (not including any kids), 2 ewes full time, plus several lambs at a time, plus 30+ laying chickens, turkeys, broiler chickens, and a big garden with room to spare! It takes a little more careful planning and management, but it works!! 
Maybe they would, I'm not sure. I just don't like stooping over all that much. 
