Is a Eurail pass actually worth it?

Only if you move every 2-3 days. If you plan on staying in one city for a week or more, point-to-point tickets bought 4 weeks in advance are cheaper.

How much cash should I carry?

Carry $100 equivalent in local currency for emergencies, but rely on a no-fee debit card for ATM withdrawals as needed.

How to plan a 3-month backpacking route through Europe

Map out a route that prioritizes geographical flow to minimize transit costs, utilizing a mix of high-speed trains in the west and budget buses in the east. Limit yourself to one city every 3 to 4 days to avoid burnout while staying within a total budget of $7,500-$9,000.

Establish a base loop. Don't zig-zag. Start in a major hub (like London or Amsterdam) and move in a logical circle or line (e.g., North to South or West to East). Do not plan more than 20 major stops in 90 days.
Identify your transport pass. If you are moving quickly, buy a Eurail Global Pass. If you are staying in regions for weeks at a time, point-to-point tickets or budget bus lines like FlixBus will be 30% cheaper.
Set the pace. Allocate 3 days for small cities and 5-6 days for major capitals like Paris, Rome, or Berlin. Build in 'do-nothing' days every 14 days to catch up on laundry and rest.
Sync with the seasons. Plan to be in Southern Europe (Italy, Greece, Spain) during the shoulder seasons (May-June or September-October) to avoid the 40°C heat and extreme peak-season pricing.

Is a Eurail pass actually worth it?: Only if you move every 2-3 days. If you plan on staying in one city for a week or more, point-to-point tickets bought 4 weeks in advance are cheaper.
How much cash should I carry?: Carry $100 equivalent in local currency for emergencies, but rely on a no-fee debit card for ATM withdrawals as needed.