You're asking advise which really can't be provided. It will be your basement - how would you like to use it? Living Space? Children's play area? Entertainment? How are others in your neighborhood utilizing their basements, or your family and friends?

You should create a to-scale plan for your space, including permanent fixtures (furnace/water heater, etc.), desired wall placement and lighting, switches/outlet positions. All you need is some graph paper and a tape measure. I suggest placing masking tape on the floor to better envision new walls.

With this, you can obtain bids. Sure you can GC yourself but are you qualified to evaluate skills and finished work, or even select trade people? Unless you're an experienced DIY'er, the cost of a GC is generally a good investment - and the project will be finished more quickly.

Our basement was DIY'ed. My schedule, and budget. I spent parts of 5 winters completing everything, doing it in strategic phases. It is primarily used as entertainment space. Linked photos have some comments below the photos. Hope this gives you one persons opinion to get you started. Good luck.

Here is a link that might be useful: Basement

If you are looking to finish it for the highest future resale value, a good resource to consult is a realtor in your area (perhaps the one you used to buy it from or sell your previous house) They will know what is desireable there. However, unless you plan on selling again soon, the desires of the market may change by the time you sell. Also, you are unlikely to recover 100% of your investment in finishing the basement so you want to make sure to finish it in a way that you are able to enjoy it for years too. If a work out room is popular but you enjoy watching movies instead, put in the theater. I will say, multi-purpose spaces are handy. If you're going to build in an office, make it meet code for a bedroom (add a closet for example) so you have flexibility down the road. A room can be an office, guest room, exercise room, craft room, or home theater (though not the ultimate theater room if its a big square with large windows) so when you are trying to sell it you can style it as whatever is popular at that point. I personally think it is very handy to always have a bath on each level of the house, but you would not likely need a bathtub. Perhaps a larger shower stall would look nice but not have the expense or size of a tub. I wouldn't go for the newest trends just to make it have a high resale down the road, you may end up just looking old and dated when you finally sell... for example, if you use a glass tile mosaic backsplash on the back of your wetbar just to be trendy, but don't sell for 15 years, it may scream 2012 when you go to sell. However, if you find a glass tile mosaic backsplash that you LOVE and use it for 15 years, it was money well spent.

Summary, decide when you want to sell again (if its 1-2 years it would make more sense to finish towards market desires vs your desires) talk to a realtor, and design a basic format that is flexible for your uses. Have fun on this project!