PLAN
I took a course on Travel Planning at Duke Institute for Learning in Retirement (DILR) which gave me a wealth of websites that can be useful in planning your vacation. I'll start by just listing them and as I explore them, I'll review what I learn. They were interesting the first time I opened them but there is so much there that they need a deeper examination. A lot of these sites were located by googling at http://google.com.
Planning a Trip in the U.S. - US travel guides on http://teoma.com
Resources - Standard all-purpose travel sites are http://expedia.com, http://travelocity.com, http://orbitz.com
Specialty sites - http://wunderground.com
To find distances between two known addresses in your destination city, access http://mapquest.com, click driving directions and enter both addresses; at the bottom of specific instructions will be distance and estimated travel time.
Travel to and in Europe - http://toandfromtheairport.com is very cluttered but has an incredible amount of info about airports all over the world and links to commercial sites like car rentals, bus services, etc. http://worldairportguides.com has far fewer airports (only the major tourist destinations, but all continents and several languages are available) but pages are far more attractive and offer a great range of additional info about the destination city.
Finding plane schedules and fare info isn't easy: US travel sites allow only trips that start in the US. One site that allows researching European options is http://europebyair.com. The "Europe travel planning index" at http://europeforvisitors.com will bring up many national airline sites, through which you may be able to find useful flight information.
Rail Travel - Information about rail travel can be difficult to decipher and some sites that seem that they'll have readily accessible info connect you through option links to sites you may have already visited. For example, http://eurorail.com connects you with http://raileurope.com. http://raileurope.com is a commercial site purporting to offer all sorts of deals and discounts and general-purpose travel arrangements comparable to orbitz or expedia. Options for "point-to-point tickets" and other headings allow determination of fares, but schedules are a problem. http://routesinternational.com seems to specialize in special-fare passes and prices but does not give schedules.
General information about travel conditions world-wide http://travel.state.gov is the web site for the Bureau of Consular Affairs. Gives civic, travel, and health-related info about specific countries, with links to relevant web sites. Examples: cites different types of tourist-related crime in different countries; legal problems travelers might encounter; available medical facilities. Provides travel advisories and warnings of all sorts; tells how to get US passport; what to do about overseas adoptions, etc.; updates on avian flu; and numerous other services.
For maps - http://mapquest.com defaults to US maps, but clicking on "maps" button brings up a list of countries. Maps are variably useful and interactive. http://worldatlas.com offers a variety of map types for different countries, varying according to how much is available. Also includes capsules of information about the countries. Does not explain the symbols! http://viamichelin.com gives road maps for countries, also links to hotels, restaurants, etc. Gives explicit driving directions, but accompanying maps tend to unhelpful. For Europe http://lib.utexas.edu/maps/europe/html offers an incredible assortment of maps for all sorts of locations, with dates and descriptions for what you click on.
Finding events and attractions - A remarkable all-purpose site that gives links to other lists of links is http://www.refdesk.com. With two or more clicks, you can access newspapers form all over the world: political cartoons; sample questions from the SAT and GRE; crossword puzzles etc. Newspapers from locations you're interested in can be extremely useful.
A mixed-bag travel information site is http://www.citysearch.com. You click on your desired city (mostly US, a lot in Australia, a few others) and get a locally edited web site, of which some are far more useful than others. These concentrate on commercial establishments more than general information.