Bill, Really!? Suki's going to be a big sister?!
I think she'll be great with another dog, but I completely understand
your concerns: You and she are certainly a couple!
I have heard both versions of the story: "When I brought a puppy home
it breathed new life my older dog"; "My older dog has never been
himself since I brought another dog into the pack".
Justin offers a lot of good comments as someone who has lived in both
a single-dog pack and a multi-dog pack. But his point about dogs
being adaptable is the most important point.
I don't have any multi-dog experience to share, but I can offer that
ordinarily it is recommended, when introducing a new dog, to introduce
a dog that is the opposite of the family dog. By that rule, for Suki,
an adult, female, larger dog, you'd probably do best with a young,
male, smaller dog. On the other hand, of course I wouldn't recommend
a dog that would take you away from Suki, one that would need you to
do things with him that Suki could not do.
Think about what kind of dogs Suki especially likes to have as a house
guest. If you've ever had a dog stay over while her or his owners
were traveling, that's probably a good indication. Maybe enlist your
friends to let you borrow their dogs for a weekend at a time or over
night?
Just to cover your bases, you could also speak with a behaviorist and
see if she can evaluate Suki and help you make the best decision for
her.
Good luck, and keep us posted!
Cheers,
Michele