Hello!
I'm no expert but I was briefly an estate agent in the area a long time ago so will see what I can remember!
West monkseaton / monkseaton MUCH nicer than parts of Whitley bay, much more desirable. Sadly i don't know those areas very well though so hopefully someone else can advise.
There are parts of Whitley bay to avoid like the plague as area becomes full of drinkers at the weekend - the area around the esplanade should be avoided. The streets behind the high street (I think it's park view?) are nice, going up to the metro station.
If its tynemouth you want but can't afford have you considered some of the flats that boarder the area in North Shields? They have the ne30 postcode and are catchment area for the tynemouth schools, but your money goes a lot further. If you put in tynemouth into zoopla but a 1/4 mile radius, it will show them up.
Lastly, have you considered royal quays type area? Or seaton burn / seaton sluice? They have been recommended to me in the past as your money goes a lot further but yet have a nice community feel.
Good luck! I am thinking of doing the move in the opposite direction ironically, and am thinking of moving from the coast over to Gosforth.
If you need any more help let me know and ill see what I can dreg up out the memory banks!