Heath,Welcome to the boards! I have a few initial comments on your travel plans.....
To begin with, I'm assuming this is your first trip to Europe so I'd highly recommend reading the Guidebook
Europe Through The Back Door. It will provide you with lots of information on things like Itinerary planning, how to use the trains, money and language issues, etc. I'm assuming from your reference to "SEA" that you're located in the Pacific Northwest, which is fortunate as you can take a quick trip to Edmonds and pick-up the book at the source (I can provide further information if required).
Although three months is a fairly good length of time for travel, I'd suggest not trying to fit too many places into your Itinerary. You're planning to cover a fairly "broad area" and you'll probably find that your trip will be more enjoyable and rewarding if you're not packing up to move to a new location every day or two. Each move to a new city will have a cost in both time and money.
Keep in mind that for visits to Russia, a Visa is required. You might leave that for a future visit?
Given the time of year you'll be travelling, I'd suggesting starting in the more northerly location (Finland) and ending up in Ireland. It will be warmer in the north during August, but by October the evenings especially will probably be getting a bit "chilly".
It would help if you could provide a list of cities and sights that you're interested in seeing, as that would provide a starting basis for working out an Itinerary.
One point to note about
Eurail Passes in general is that these DO NOT include the reservation fees that are compulsory on some trains (usually the fast trains such as the TGV in France and others). These must be paid separately. DON'T be caught on trains in Italy without a valid reservation,
as you'll be fined on the spot and it's not cheap (trust me on that one)!You might find it worthwhile to obtain a membership in
www.hihostels.com/web/membership.en.htm before your trip. While this won't provide any advantages to stays at independent Hostels, it will provide cheaper prices and preferred booking if you stay at
HI Hostels. As they're part of a chain, the facilities tend to be fairly consistent from one location to the next, and they usually have some good locations in most cities. In most cases, sleep sheets are provided in the cost of the room and breakfast is
usually included as well.
A budget of US$ 75-100 per day is probably a minimum amount to consider, as US$75 is only about €55 at today's exchange rates. If you're paying €30 per night for a Hostel, that doesn't leave much left over for food or incidentals. I'm assuming you're not including your air fares or rail pass costs in that amount?
Depending on your route, budget airlines may be a better option than rail but it's difficult to provide examples until your Itinerary is somewhat "roughed out".
Hopefully the others will have some comments also.
Good luck with your planning!
