From what I have read, the Baedeker raids focused on attacking towns & cities of the UK based on cultural importance as retaliation for bombings of locations such as Rostock. How were these targets identified given culture is harder to quantify than something such as industrial capacity, and what led to the inclusion/exclusion of sites?
Have noted Stratford due to the obvious cultural link, and that not all targets seemed to be especially large (notably seems Kings Lynn was hit)
Hitler's directive that launched the 'Baedeker' raids ordered:
"... that the air war against England be given a more aggressive stamp. Accordingly, when targets are being selected, preference is to be given to those where attacks are likely to have the greatest possible effect on civilian life. Besides raids on ports and industry, terror attacks of a retaliatory nature are to be carried out against towns other than London."
The raids got their name when Gustav von Stumm of the German Foreign Office announced "we shall go all out to bomb every building in Britain marked with three stars in the Baedeker guide", which would be tricky as a single star (or asterisk) was used in the guidebook as a mark of commendation, with a few particularly notable places receiving two stars. The primary targets (Exeter, Bath, Norwich, York and Canterbury) were historic cities, but just as importantly for the German Air Force they were weakly defended; the majority of German strength was on the Eastern Front, and British defences had greatly improved from the winter of 1940. There don't appear to be particularly compelling reasons why they were chosen over others. Stratford-upon-Avon, being a relatively small town, wouldn't have had a great effect on civilian life; Shakespeare's House may have had cultural significance but hitting a specific building was generally beyond the capabilities of night bombing at the time (on the first raid on April 23rd only one of 40 aircraft actually hit Exeter at all, the rest scattered bombs across Devon, Cornwall and Somerset).
Jan Gore, in The Terror Raids of 1942: The Baedeker Blitz, draws a distinction between attacks on the five mentioned cities and other German raids in 1942, noting Poole, King's Lynn, Great Yarmouth, Ipswich, Bedford, Birmingham, Grimsby, Hull and Southampton "... had some military significance, and were not, as such, Baedeker raids". Richard Overy in The Bombing War records June attacks on Weston-super-Mare as being on the list of Baedeker targets despite the fact that "its cultural value was at best modest"; Gore notes that there were two aircraft factories there, and posits that the return of Winston Churchill by flying boat from America may have been another motive should he have been staying there after the journey.