Thanks very much for the essays, I think they'll be very useful.
With Tacitus, he often comes up as the primary source in my Rome A2 unit and his works, namely the Annals, are of varied reliability and accuracy. Like many, his accounts were written after the deaths of those he was writing about and so only Domitian onwards were contemporary. This is only the smallest problem; as the Annals is an incomplete work, we are missing years worth of information from the reigns of Tiberius, Gaius, Claudius and Nero.
More importantly is his bias: Tacituslived in fear of Domitian's reign because of the feud between theemperor and the senatorial class, whom Tacitus was among. Thisinspired in Tacitus a tendency to exaggerate the negative in everypre-Trajan ruler, showing how their reigns were invariably andincurably corrupt. His writings reflect official policy in Trajan's time and treats him more favourably. Nonetheless; Tacitus definitely had a pro-senetorial/oligarchic bias and an anti-autocratic one, and you can infer a dislike of the imperial rule as a whole.
I've always used inscriptions in the same way, as supporting/contradictory evidence, as the case may be. I just wanted to see how other people tended to use them, as they can be a bit more difficult to work into an essay if you can't think of a literary source to compare them to.