Galle Fort is one of the best-preserved colonial fortifications in Asia and it knows it. The streets inside are genuinely beautiful - Dutch architecture, jacaranda trees, boutique hotels in 300-year-old buildings. Prices inside the Fort reflect this. You're paying for the atmosphere and most guests think it's worth it.
Staying outside the Fort and visiting it as a day trip is a common mistake. The Fort at dawn before the day-trippers arrive and at sunset when the light hits the ramparts is a different experience entirely. Book inside the walls if your budget allows.
The south coast in peak season brings crowds. Unawatuna beach 3km away gets extremely busy. Galle itself stays manageable because the Fort is a contained space. Two nights gives you the Fort properly, a beach day, and a morning at the market.