I cycled through all of the Americas and the Guyanas were one of the most interesting parts. It was a welcome change in food and culture and language after a year in Central America and Colombia/Venezuela.
The silly thing is that there is no border crossing from Venezuela (though thet share a long border), as Vz claims a large part of Guyana... So we had to cycled down to Boa Vista, Brasil, and then back up to Lethem in Guyana. I assume that there are also internal flights in Brasil to Boa Vista, so that could be another way of entry (the bus to Guyana is only a few hours and there are daily buses to George town).
We only spent about a week in each country as we had to catch a boat in Macapa, but I really enjoyed them, Surinam the best, but the Guyanas were nice as well. As mentioned, we cycled, but had no problems with safety (actually, after crossing 23 countries, the only trouble we had was in Argentina, but that is another story..).
We got the visa for Guyana in Caracas, Vz; The visa for Surinam can be gotten there as well, but takes weeks (!), but fortunately in Georgetown you can get it in a day ('we do things differently, here', was the answer to my question to the embassy in Guyana. The Surinam embassador in Caracas actually recommended illegal entry into Surinam instead.).
You go from one country to the next by boat/ferry, easy. Wonderful to see in French Guyana were the leatherback turtles depositing their eggs just outside of Cayenne. The road into Brasil is a bit dangerous, so we got a ride to the Brasil border.
In short: worth a visit, off the beaten path.
Cheers.
