Hi celticheart, I've read a fair bit of Nigel Tranter's works and do like them. the only reservation is that in many of the novels concerned with slightly less intense times than the ones you mention, the storylines are almost identical.
What is good though, is that they are very true to fact. There is some degree of fictionalisation, but all the events happened as written. And as a student of Scottish history, these are really helpful!!!
I think Kenneth is one you should definately read, plus some of the ones prior to 1296, when they were still the Kings of Scots, and not the House of this, that or the other.
I've just finished reading Warden of the Queens March, about the reign of Mary, Queen of Scots and am desperate to read david the Prince, but I'm too busy to read it any time soon!
Open up The Original Pipe Box!