There are some things you should know about lepto vaccines before you make your decision. First off, from a discussion about vaccines with my repro vet, the majority of lepto vaccines do not last more than 6 months and some are ineffective after as little as 3 months. This is because lepto is a bacteria, just like bordatella so just like bordatella vaccines the efficacy is far less than vaccines for viruses. Secondly, lepto vaccines only vaccinate for a limited number of serovars, I can not remember the exact numbers but it was less than half of the known serovars for lepto. So even a vaccinated dog can still get the disease. So you need to know what serovars are common in your area and whether or not those serovars are covered by the vaccines otherwise you could be gaining a false sense of security. I am very lucky to have vets that are very honest with me. My regular vet has stopped vaccinating for lepto because the serovars in our area are not the ones in the vaccine so the dogs would still be at risk plus have the added risk of vaccine reaction.
If you are going to get Lepto done then do some research on what Lepto vaccines are available and what their efficacy is. You may want to tell your vet that you would like to separate Lepto from the other vaccines so if there is a reaction you know what it is to. Also, if you find a company has a more effective Lepto vaccine you can choose to use that one.
Here is the vet handout from Intervet on some sample protocols for dogs using the Continuum 3 year vaccine. On these protocols Lepto would be given as its own separate vaccination so you do have some options.