China's defense is as much economics as it is military. Those important Chinese coastal cities create as much wealth for American and other western nations as they do for China, and much of the world has become quite dependent on Chinese exports. To 'raid' those cities would be like cutting off your nose to spite your face, to use an old saying.
In terms of sheer military power alone, the picture isn't very clear cut either. The US has only a few air bases within range of China, all of which are not hardened and within land based missile range of PLA forces, never mind air and naval launched weapons. It will be extremely difficult to operate out of those bases for any length of time, and almost impossible to do so without heavy losses on the ground.
Without total air dominance, the US will never risk its precious B2s. They might be effective against fixed ground based SAMs, but they are by no means invisible to radar. What more, they are said to be detectable by low frequency radars. Not good enough to guide missiles with, but certainly good enough to vector in fighters. Once you get a powerful enough radar emitting close enough, any stealth target will show up, especially if its getting illuminated at an unfavorable angle, such as from above.
Point being, if you send B2s in unsupported, then there is a very good chance they will get shot down.
That means that the primary strike assets will have to come from USN carriers. In this game, detection is key. If the PLA can find the carriers, they can kill them quite comfortably since the PLAAF and PLANAF has enough strike aircraft, subs and FACs etc to launch more than enough missiles to completely overwhelm a carrier battle group's defenses. And with China relying on Chinese weapons and China's industrial capabilities, it will go for overkill and such a strike could easily wipe out an entire battle group with plenty of missiles to spare.
Until the F35 comes online, the USN's primary strike aircraft the FA18E does not enjoy many advantages against current front-line PLA fighters, so even if the PLA has trouble finding the carriers, the strike packages coming in will still have a very hard time. Especially if you factor in things like ground and PLAN naval radars and missiles, as well as the PLA's own AWACS and tanker Assets.
If the US brings all 11 carriers as well as all its SSGNs and most of all its fleets as well as be willing to take heavy losses keeping their island airbases open, then they can overwhelm the PLA conventionally. But it will come at a very heavy price, certainly at an exchange rate that will make US generals and politicians bulk. And that is not factoring in the very real possibly that the PLA might resort to the use of tactical nukes if things really started to go south for them.
The US would then be left in a very difficult position. If the PLA used nukes on US naval assets, a tactical nuclear strike against Chinese military targets based on the Chinese mainland could easily be seen as an escalation into the strategic use area, as no-one can tell exactly where the nukes will land until very close to detonation. But the PLA would be able to tell pretty early on that the American nukes are aimed at mainland China, so they may mistake that for a full strategic strike and initiate MAD against the US before the US missiles hit.
Even if the US does risk it and launch tactical attacks, its still a bad trade for them, as they loose their navy in exchange for PLA forces that must already be pretty battered at this stage to force Beijing into the use of nukes in the first place.
War between nuclear powers are always filled with massive risk and uncertainty. That's one of the reasons two nuclear powers have never gone to war with each other yet - there is just no way to tell where that will end, so all sides have been more willing to seek out peaceful compromises.