Any first visit is just that, a first visit. I think impossible to determine if this is the woman you want to marry or the same for her.
It seems to be easier to make several visits in each direction and to also augment this with lots of letters and Skype conversations. The distance does not change the relationship, except for the particulars. Yes, you cannot hold hands while talking on Skype, but this is part of the process.
It is difficult for a Russian to have a visa. Easier it seems for a girl from Ukraine for instance. But if two people wish to meet, they will manage. And having a vacation together does not give enough information to decide to marry. Developing a real relationship takes time. This is not a race. I spent almost two years with my last girlfriend. It was not a waste. We did not end up together but we both learned from it and enjoyed the process even if painful in the end.