Why Czechia
Prague came through the twentieth century without major destruction, and that is the exception in Central Europe: Gothic, Renaissance, Baroque and Art Nouveau coexist there in the same district, intact. That is what explains the crowd, and it is worth it despite them.
The rest of the country is largely ignored: Český Krumlov, Kutná Hora, Olomouc, South Bohemia and its ponds, the spa towns of the west. An hour by train from Prague is enough to find space again.
Getting around
Trains and coaches are cheap, punctual and comfortable, with private companies competing on the main routes and offering assigned seats for a few euros.
Prague is walked, and its metro is simple and quick. The ticket is validated in the small yellow machine at the entrance — an unvalidated ticket means a fine, and plain-clothes inspectors are frequent in the centre.
Money
The currency is the koruna, not the euro, and businesses that accept euros apply an unfavourable rate. Paying in koruna is always better value.
Avoid the exchange offices in central Prague, whose commissions are predatory, and systematically decline the conversion offered by ATMs and payment terminals — choosing "pay in CZK" saves several per cent every time.
Before you go
Taxis hailed in the street in Prague are a classic trap. Apps and telephone bookings give a price in advance and settle the question.
Beer is cheaper than water and is part of ordinary life; the tolerance for alcohol at the wheel is zero, with no margin.
In restaurants, everything that arrives on the table is charged for, including bread and unordered appetisers. Politely refusing them is accepted.