I am new to domaining and am looking to start as more of a hobby/long-term investment.... Can I realistially "park" them with a company and have all the monthly/yearly fees paid for so there is no out of pocket to keep my domains? I am not looking to spend a whole lot of time as far as building/management.
Most of the time, parking won't get you enough money to keep your domains, sorry. (Unless you are planning on building traffic to your domain names)
Parking a domain that has no traffic will not earn you money. It's also against the terms of service to send traffic to a parked domain. Unless you're buying domains that already have traffic, it's not worth it.
buy and display some useful related content and display ads in them, it will give you back some money and value will increase.
So I can't really just buy a random domain that I would like to sell in the future... and just park it... I have to spend some time getting some traffic to pay the monthly and yearly costs?
Sedo is Ok. Try Bodis, Parkingcrew or InternetTraffic. I am using Frank Schilling's Internet Traffic now and so far no big results. Godaddy Cashparking is ok but it can be hard for people to see your "For Sale" Banner.
You can use a parking site that will SEO your domain parking page for example I use seoparking.com for my new domains and they optimize domain parked page with free articles that can help to develop your domains. Truly, parking that does not give you opportunity to optimize your domain can not pay you. Unless you just want to park and wait until you have time to develop the domain. It is better for you to use seoparking.com they have affiliate link but I am not going to get any cent from this introduction. Cheers.
In short, you would be much better off developing quality websites as it could be much more rewarding.but if you want to park...I have had a decent experience parking my domains via GODADDY. I tried parked & sedo, and they were not any better than GoDaddy for me.
if you would like to buy domains in godaddy, i would like to help you buy tehm,50 domains $6 per domain, and then i can push it to your account, we can make a deal through ebay
parking is depnd on your domains traffic its no use if you domain don't get any traffic i have parked all my domains in bodis ill get few $$ a month
sedo is best company but i think new domain will not have visitors so will not able to earns try to get used domains