There are lot of them.
Some of them that comes in my mind right now:
Вам удобно говорить?
Могу я с Вами поговорить?
Я Вас не отвлекаю?
Вы не заняты?
They are very official. You can make it more confident, but still respectfull by omitting "Вы/вам" part:
Удобно говорить?
Можно поговорить?
Не отвлекаю?
Не заняты?
It's like "we are too long term partners to spell redundant words".
In case of close relations, like friendship, it is normal to say "Ты".
Тебе удобно говорить?
Я тебя не отвлекаю?
Ты не занят?
("Могу я с тобой поговорить" is a little more official by it's nature)
But note, that shortage of first two of them are the same as in case of "Вы":
Удобно говорить?
Не отвлекаю?
"Respectfull plural" is not observable here. You must say it before previous shortage class:
"Леонид Михайлович, здравствуйте! Не отвлекаю?" ("вы" is implied)
vs
"Леня, привет! Не отвлекаю?" ("ты" is implied)