Fitting Oxford into a day with Windsor Castle or Blenheim Palace

Day one: Leave Heathrow drive to Oxford; drive to Blenheim (spend night Bladon or Woodstock.)
Day two: Drive to Bath; drive to Chipping Campden (spend night in Cotswolds)
Day three: Drive thru Cotswolds to Windsor. Or it could be done in reverse. I think from what you want to see in Oxford you will need more time than you think. Blenheim is only 30 minutes from Oxford. You can spend the night near there so you will be fresh for your time in Bath. We did a lovely drive thru the Cotswolds visiting several main streets of the picturesque villages but did not feel the need to linger. Windsor could be interesting if you do a castle tour. Bon Voyage.

We did a full day in Oxford. I think your plans for Oxford provide at best half a day, which is not enough time. We have done Windsor Castle and it used up a bit more than half a day, counting transportation to and from. Also, Blenheim Palace is a half day event. I don't think the Palace opens until 10am. You will probably finish about noon, at best.

I don't think that is enough time to do either justice. Oxford can take an entire day - and you want to fit in the "big stuff," which will shortchange it if you only spend 1/2 day, IMHO.

I would opt for touring Windsor Castle in the morning (it's very cool, and I think teens will love the pomp of the guards ceremony). Then I would pick up a couple of large servings of the FABULOUS chips they sell at the chippie right outside the castle entrance, and walk into Eton. It's not far at all (just over a mile) and it is just beautiful. I've been a couple of times in fall, and can only image how PERFECT it would be a gorgeous June day. :-)

Along the way you cross the Thames on a cute little foot bridge, get to watch the masses of lovely swans on the river, and then saunter down Eton's adorable and super quaint high street toward the college.

There are pubs and cute little restaurants along the way. Eton College is brilliant - tons of old stuff to gawk at - and the whole day would be just relaxed enough (while still jam packed with sights) while also giving you a view of a storied English school.

I don't think you can fit in Oxford in that amount of time---especially with what you want to see there. I would do Windsor Castle and perhaps take the other suggestion to walk over into Eton before going on to Bath.

You mention leaving Bath at 7:30 a.m. If you're not traveling to Bath to see sights there, why not go onto Chipping Campden for two nights there? One night stays are much tougher IMHO.

I would slow down a bit and savor fewer things rather that be running from place to place.

Parking in Oxford is nonexistent, unless you park at the lot away from the city.
Take the train to Oxford and when you plan to depart pickup your rental car.

You need a full day to do Oxford. You can do Blenheim Palace in half a day. Bath takes a full day, consider the Brooks Guesthouse. Also, for the best fish and chips ever, dine at the nearby Scallop Shell.

Check the opening times for Blenheim, it may not be open until 10am.

Chipping Campden, I recommend the Volunteer Inn, it had great rates and the best pub in town. Also, a great Indian restaurant.

It is not possible to do justice to either Blenheim Palace or Oxford if you try to see both on a single day. Oxford alone can easily be a day and a half. Blenheim Palace has large grounds Which take serious time to cover and appreciate. Pick one or the other.