My dryer vent doesn't even go outside so I don't know much about venting one through the wall or attic. My dryer vent leads to a container filled partly with water and surrounded by fine mesh. It works fine and doesn't create lint. I do have to clean out the lint once in a while and fill up the water. And it works great as a humidifier in the wintertime.

I would recommend going throught the attic as a last resort. Ours vents on our steep roof and maintainence is a nightmare!!!! We have to call someone to come out to clean our vent line since the roof is such a steep pitch. We've had trouble with the flaps sticking up and birds getting in the vent line = ewww! = maintenaince call. Put chicken wire over vent to prevent birds = clogged vent = wet clothes = another maintenaince call. This is our current status.
This has just been our experience. I'm sure (I hope) there are others that have sucessfully vented through roof. The fans you mention I believe are for those that have a longer vent run and need the extra push to get the air out. Depending on your attic height you may or may not need one. We didn't.
Another option is what davey3000 has, a condensing dryer. They do not vent outside and the moisture from cloths collects in a pan or can set up to drain into a floor drain. These appear to be a bit less efficent energy wise but are gentler on clothing. Bosch makes a nice condensing dryer.
Good luck in the final stage of your house!!
Anyway my 2cents worth.

Amm0810 be aware that Davey3000 has a regular **vented** dryer, not a condenser one

Condenser dryers **condensate** moisture (turn steam into water). This water is stored in a tank inside the machine (that has to be **emptied* ) or pumped away like washers do. No matter how they get rid of water, they **don't** release any moisture in room air

Your best bet is to vent through the outside wall as close to the dryer as possible. If your dryer has a good lint screen, you won't have much lint accumulating outside the vent. If you have shrubbery or planting in the vicinity, you probably won't even notice any lint. If the walkway area is all paved, a quick sweep or walk-through with the leaf blower (or a breeze, for that matter), will make things tidy in no time.

Venting up through the roof is not a good proposition. You'll need a much longer duct run, which isn't very efficient and will lead to longer drying times, you're likely to eventually end up with a clogged vent duct, or one that will need more frequent maintenance, and if your roofing material is composition shingles or some other snaggy surface, you'll end up with a gunky, inaccessible mess around the vent outlet. You don't want to go there.

You don't want the bucket with water solution either -- unless you want everything in the laundry room coated in dust, you like dust bunnies, and you enjoy high humidity levels causing mildew and mustiness.

Dryers work the best with the shortest, most direct route outside. Going up through the attic is not a wise choice, unless you have no other options such as living in a condo and so forth. Using those water filled containers is not good in humid climates, and why would you want to do it if you are running the AC in the summer if you live in a warm climate. I would just let it vent on the walkway, and you will have to keep any excess lint cleaned up. All dryer vents need to be cleaned from time to time, and AMM0810 is right, its a nightmare to clean them when they are on the roof.

davey3000, hopefully your Dryer is electric.

NEVER vent a Gas Dryer indoors.

Mine vents through roof as well......STEEP PITCH......I got the ladder, got up to the roof and once you're on the roof it's MUCH more intimidating than it looks so I will NOT go up there again. I took the chicken wire off the cap because it was clogging with lint. Here is what I do to clean it and it seems to work good. I pull the dryer out about every six months, use an electric leaf blower (200 mph I think) and blow it and someone stands outside watching and says that lint comes FLYING OUT..Sometimes I do it more than twice a year just to be safe. I know this is working because of the amount of time it takes for clothes to dry.