I’m not sure exactly where this is, there being a few possible places called Suffolk Street or Great Suffolk Street etc.
Suffolk Street (sometimes called Great Suffolk Street) first appears in the rate books in 1664 and reference to Morden and Lea's map of 1682 (Plate 1) shows that it was approximately on the site of the present Suffolk Street. Little Suffolk Street, which was first rated in 1672, was further north than the present Suffolk Place and extended on the east side of Suffolk Street to Whitcomb Street (then Hedge Lane). Strype, in his 1720 edition of Stow, tells us that Suffolk Street "is a very good Street, with handsome Houses, well inhabited and resorted unto by Lodgers." The Earl of Suffolk is rated there in 1666–82, and the Earls of Thanet and Carlisle were there in the 1680s. Most of the earlier residents could be classed among the lesser gentry, ambassadors, (fn. n4) doctors and the like. In January, 1667–68, Pepys notes that the King had furnished a house for Moll Davis, the actress, "in Suffolke Street most richly, which is a most infinite shame." (fn. n5) (fn. 39) One of her neighbours, Sir John Coventry, shared Pepys' opinion and expressed it too openly in Parliament, with the result that in December, 1670, he was "sett upon in Suffolk Street as hee was going to his lodging with several persons on horse-back and on foot" and his nose was slit. (fn. n6) (fn. 139) http://www.british-history.ac.uk/survey-london/vo…
The Suffolk Streets in question are on this 1674 Rocque map
Chart showing the number of references in each month of the diary’s entries.